Modern oil for Eagle engines

[Canoe]

Faced with an oil change, and an oil standards update for 2020, I ended up going down the rabbit hole of the seemingly millions of opinions and tons of data on bobistheoilguy.com.

I've got a completely rebuilt 258/4.2 straightened then bored to 4.3, plus a decked 4.0 head (7120) plus stronger valve springs, 4.0 basic header, a wider cam (Baja Beast street legal), high voltage coil & updated ignition module & wires & plugs, and a dizzy that was custom matched to that setup, running Castrol 10W-30 with a ZDDP supplement, along with an offshore MC2150 carb. Somewhere between 20,000 km and 30,000 km on it. So old design with some slightly newer components, but not an old worn engine.

The consensus seems to be:

• With a modern oil, they're so improved over the oils of our Eagle's era, most engines can now be safely run with the xW-yy for the actual temperature range they'll be run at.
• Generally much better additives, for getting the xW-yy, for cleaners, for anti-corrosion, etc. - except for lowered anti-wear additives that are suitable/needed for flat tappet engines...
• Flat tappet engines still need something, be it a Zinc/ZDDP additive, Zinc/ZDDP replacement, or an oil formulated with such for older engines ($).

AMC doesn't get much love, but Jeeps, even early Jeeps do.

Without going to one of the premium & expensive high ZDDP oils formulated for older (flat tappet) engines, the toss up for a 4.2/4.0 era Jeep flat tappet in an SN rated oil seemed to be between Mobil 1 or Castrol Edge. I'd have liked Castrol Edge Extended Performance (better additives which last longer), but it isn't available in the xW-yy grade I wanted. (And over SN, I'd like the latest SP rated oil too, but it's too new to have wide choices yet.) The Castrol Edge is thought to likely be slightly better than Mobil 1 for Jeep engines, due to a better match of its additives to the needs of that era of engine. Both would still require some user added additive for flat tappet.

So after dozens of threads, I was going to go for Mobil 1 0W-40 SN Euro Formula, plus a Zinc/ZDDP Replacement, to get the 0W on one end and 40 on the other. I'd have preferred the Castrol Edge 0W-40 SN Euro to start with, but where I am it seems to only be available by quarts/litres, not jugs, so too costly.

However, using Shell Rotella T6 was highly recommended. As it is a diesel formulation, compared to modern gas engine formulations, T6 has meaningfully elevated levels of phosphorous and Zinc/ZDDP (added for valves on diesels). This means it also provides a level of flat tappet protection in the oil from the start. And the best flat tappet protection is claimed to be from a mix of oil with 'some' ZDDP and the addition of zinc replacement polymers (~1/10 the wear of just ZDDP or just polymers). T6 is said to have lots of cleaners, but in reference in using it in gas engines 'who needs an engine that is that crazy clean'. It was also claimed that some moly in the SM formulation was reduced or removed in the SN formulation. T6 in 5W-40 and 0W-40 used to show with a gas engine rating of SM. Post SN specs and updated T6 formulations, the gas engine rating was removed from the packaging. This was attributed to both a change in the specs and stricter enforcement on claiming a rating. A BITOG post pointed out that on the Shell web site, the new formulation of T6 5W40 doesn't have a gas engine rating, but the T6 0W40 is rated SN - it's just not promoted on the packaging.

So after juggling the facts & opinions around in my head, I reminded myself that any SN oil is so much better than any oil I've ever used in the past, I decided to throw the dice at Shell Rotella T6 SAE 0W-40 (SN). Conveniently, its jugs are 5.0 litres, so I can do an oil & filter change for 4.7 litres, and have oil left over. Which will be handy in a week or two when I swap the new filter for another new filter after it's run with the T6 cleaners for a while, then add in the zinc replacement additive and top up the oil.

OMG What a difference with this oil!
It's only 5 C (41 F), but the engine very noticeably turns over faster, starts faster, and runs smoother. The prior minor but constant noise of valves or lifters (don't know which - suspect lifters) is gone at idle, normal accelerating (including up hills), and at cruising. To test, punching it, a minor amount of that noise returns during the punch.

Time will tell, but so far, I'm seeing apparent improvements I didn't expect.

[MIPS]

I don't do anything high-performance with my Eagle to mandate adding zinc with my oil but I've always stuck with 10W-30 as per the temperature range chart and I've never run into a problem or cold running sluggishness down to -25. Even that stuff is better engineered now than it was in the 80's. While I'm sure full synthetics are even better I can't justify the cost:performance ratio that would be in a 258 new or old.

Lifter tap? Sure I had that as well until I replaced them but that should be going away regardless in the first second after a cold start or you got bigger problems lol.

[Canoe]

Using a zinc/ZDDP supplement or replacement, or using synthetic, is not about engine "performance" per se. It's about oil doing the best job in aiding the longevity of the engine.

With tougher vehicle emissions standards, there was updating of oil specifications required as part of meeting the emissions standards. The oils we buy off the shelf has for years had greatly reduced levels of the old anti-wear additives (added by the manufacturer) that went hand-in-hand with our engine designs. Those reductions increases wear on flat tappet cams. Hence the general recommendation for the user is to add their own additive to return the oil they're using to meeting the needs of flat tappet cams, or to buy one of the expensive formulations with those additives for older engines with flat tappet cams.

Back sometime in the 90's, I switched over to full synthetic 10W-30, to get more oil staying up on the internal parts, so there was less wear & tear on startup. I wasn't expecting it, but I was blown away by how easier my 258 turned over. After cold nights, instead of turning over to RrrrrrRrrrrrRrrrrrRrrrrrRrrrrrRrrrrr before it would start, it was RrrRrrRrr, and away it went. That was back in the 90's when a really cold night was -25 C (-13 F). (It even started faster in summer temperatures.)

In recent years, we're seeing a number of winter lows down to -35 C (-31 F). And if I go up in the hills a little north of here, that's common, with occasional dips to -45 C (-49 F). 10W just wasn't cutting it anymore for startup. I wanted meaningful oil flow sooner without bypass for getting reduced startup wear. And with summer temperatures now hitting upper 30s C with some 40 C (104 F) touches, and my desert trips taking me into areas with periods of highs going into the 40 to 45 C (113 F) range, the 30 wasn't leaving me comfortable on protecting the engine.

The recent noise in the engine was bothering me. I've been getting that since last summer with with the increased summer highs, on an older spec 10W-30, and this year it stayed into fall. Not a lot of mileage since the last change, but long in time. It was time for an oil change. And that change removed that noise (except when I punch it (always has) - which is rare to encounter a traffic situation where I need to jump out of the way to avoid getting hit, or need to quickly make a little more distance between me and someone doing something stupid or dangerous).

Oil viscosity at low temperatures by the W grade is interesting.

[vangremlin]

Thanks for sharing your research and findings!

[Canoe]

Minor update

[...]Shell Rotella T6 [...] in 5W-40 and 0W-40 used to show with a gas engine rating of SM. [...] A BITOG post pointed out that on the Shell web site, the new formulation of T6 5W40 doesn't have a gas engine rating, but the T6 0W40 is rated SN - it's just not promoted on the packaging. [...]

After SN specs, at first the T6 0W-40 packaging was showing "CJ-4/SN", just as the prior formulation showed "CH-4/SM". At some point, the SN was dropped from the packaging. Online purchase sources may show T6 0W-40 images with an API Service of CH-4/SM, CJ-4/SN or CJ-4, depending on when they updated their images. You may wish to confirm that they are selling the CJ-4 version, not the old stock CH-4 version, to known that you're getting the SN and not old-stock SM. SM is still very good, but if T6 is your choice, and you can get the updated SN, why not.

[Canoe]

... I decided to throw the dice at Shell Rotella T6 SAE 0W-40 (SN). ...
OMG What a difference with this oil!
It's only 5 C (41 F), but the engine very noticeably turns over faster, starts faster, and runs smoother. ...

Crazy!
It's gotten every smoother and quieter. I'm guessing due to cleaning out and getting into all the places the old oil had claimed.

Prior to this oil change, I would typically need two full press & release of the gas pedal, then a press & hold, then turn the key to start. Now, and we're down to freezing, with a cold engine sitting overnight, one full press & release, one press & hold, and upon key it turns over and starts in around a quarter second. Astoundingly, it seems to be three Rrrs in that time. With the engine warm but freezing outside, it takes one press & hold, and upon key, it turns and starts up so much faster than a quarter second, I can't estimate how fast.

Of course I've no idea:

• if it's due to this specific oil (with its flat tappet friendly if limited additives), or
• if I'd get the same results with this grade of oil (0W40, which I've never used before), or
• if I'd get the same with any appropriate grade of API Service SN oil.

It's going to be interesting to see how the oil looks when I swap in a new filter.

[Canoe]

Temps are going around -10 C (14 F) overnight, and highs in single digit C (just above freezing).
With a cold morning start at those temps, I've had to return to press the throttle for two press & release before a press & hold, then turn the key.

While turnover is immediate and easy, as is starting, it appears that having a low W oil does not replace warming the engine up. On startup at these temps, the engine is very noticeably noisier than it is at a start around freezing, and meaningfully nosier than once it has warmed up. Takes a good thirty seconds of idle before it sounds like it's ready to drive. And it's another two minutes before it sounds fully smooth.

An oddity. My nephew's ride is standard transmission; hold the brake pedal down before it enables a start. I've been driving his by times. So on the Eagle, without thinking I applied and held my brake pedal for the start. Startup was immediately smoother than starting without holding the pedal down... So as an experiment, I kept doing that. It's a noticeable difference, an improvement.

My guess: brake pedal depressed before startup, there's less vacuum volume in the brake booster, so the vacuum lines are at their desired vacuum sooner, so spark timing is correct sooner. Once the engine has a couple of seconds of running, tons of vacuum available.

[Canoe]

So call it a month and a half running with Shell Rotella T6 SAE 0W-40 (SN).

Engine starting, above or below freezing, is back to "typically need two full press & release of the gas pedal, then a press & hold, then turn the key to start". Continues to turn over really easy.

But the engine runs smooth! And quiet.

At normal accelerations, and with adding a bit for getting out in traffic and such, the engine just seems more responsive and so very smooth to changes in pedal inputs. All purely anecdotal. It also seems to provide a given acceleration more easily with less pedal required, so willing to easily almost effortlessly spin up, and without feeling like it's putting any stress on the engine or chassis. I can't find the words to exactly describe it. Like it's nicely quiet and easy like a 'grampa' car, but no lag while providing acceleration character much more towards that of a performance car that isn't being driving anywhere near its limit.

Can an oil be providing so much less friction (from oil friction? cleaner parts?), that it provides any discernible improvement, let alone such a discernible improvement? Or has the rebuilt engine finally reached a sweat spot in wear & clearances? Or this oil matches the engine's current wear & tear?

[TheBirdman]

Yeah, theres a huge amount of friction caused by oil flow in the engine. So much so that on a real high performance engine, you can see an increase in top end horsepower just from running the engine a quart low on oil. Theres a reason its suggested to get tougher oil pump drive gears if you run a high flow oil pump, the extra load can chew the stock gears right off on some engines. The only problem with going with lighter oil is if youre running a lower base weight oil that the motor was designed for, youre putting a lot of trust in your bearing surfaces, cause if anything goes wrong and causes a momentary obstruction or drop in oil pressure, youre going to have metal to metal contact a lot quicker than running a base weight of 10, 15, or 20. Almost every engine Ive ever pulled apart has shown some kind of damage to the main bearings, either from a little chunk of something making it past the filter, or acidic oil, or something, and the engine still ran perfectly fine, because between the oil viscosity, shear strength, and the volume the pump puts out, theres generally enough safety margin that it takes some serious neglect to harm a bearing to the point where it starts self-harming.
TLDR: Im happy for you, and Id never tell someone how to run their own engine, but youll never see me butting anything lighter than a 10 base weight oil in my eagle. Id rather have the extra safety margin on a 150k mile motor than a little less friction.

[Canoe]

Interesting that there can be that much of a difference is flow resistance.

... The only problem with going with lighter oil is if youre running a lower base weight oil that the motor was designed for, youre putting a lot of trust in your bearing surfaces,...
TLDR: Im happy for you, and Id never tell someone how to run their own engine, but youll never see me butting anything lighter than a 10 base weight oil in my eagle. Id rather have the extra safety margin on a 150k mile motor than a little less friction.

Makes sense. But that's for something that may happen. For cold starting, that is something that does happen. And frequently.
So the damage you've observed, did that happen from something that may happen, or from something that does happen.

The '82 Eagle manual & TSM shows that for Lowest Anticipated Temperature of 0 F (-18 C), they showing 5W-30 or 5W-20. So the engine should be designed for 5W. I have seen an Eagle manual graphic with more grades specified, but I can't find that now.

The stress on gears, plus oil filter bypassing, plus low oil flow/pressure, with trying to pump oil that is like cold maple syrup or even molasses, is something that happens at those temperatures with an oil of 10W-. With minimum temperatures at or above -20 C (rarely to -25 C) and with synthetic 10W-, I had no problem. Prior to that, it was a Texas car; I don't know what they used - it was pretty thin. When my engine was rebuilt after the warped head took it out, the mechanic showed me the parts and how the bearing surfaces were good except for the new damage. Since I bought it, I've used the Carquest Blue (Wix) (don't know what I'll use now that the Carquest aren't Wix anymore...).

- I will regularly be starting as low as -25 C (-13 F).
- I will have periods each winter of starting as low as -35 C (-31 F).
- On occasion, I will be starting as low as -40 C or even -45 C (-49 F).
At those cooler temperatures, the engine was not happy turning over with 10W-, even though it was synthetic.

So at the temperatures I will be starting the engine at, I have to go with what will happen, not with what might happen. Especially since going for a viscosity for what might happen will make things worse with what will happen.

An oil grade vs. temperature chart made for more modern oils shows an expanded operating range for 10W-, down to -30 C (-22 F).

At least 0W- at 40 for 0W-40, covers -40 C to + 40 C. My anticipated extremes is just outside of that, -45 C to +45 C, so I should be running 0W-50. Except for an oil heater, I can't do anything for a lower temperature, but I can drive slower and gentler when I'm up around 40 C. 

[Freeagle]

How many 4.0L's are running around out there with 200,000 miles or more using regular old cheap house brand API SN 10w-30 with low ZDDP? A lot, and yet we are not hearing of hem eating cams and lifters left and right. So, your 258 is probably fine too. But, if you are like me, you like peace of mind and an extra margin of safety. That's why I like Rotella T4 10w-30. I have personally sent off samples to laboratories for testing and it tests with 1100 ppm of zinc and 900 ppm of phosphorus. That's not super high, but it's high enough and it's higher than API SN oils.

A recent fire at Shell's additive plant made Rotella scarce and more expensive. I was considering finding something better anyway, and that's when I switched over to AMSOIL Z-Rod oil. It's specifically made for classic car engines. I happen to be an AMSOIL dealer, so I get it at wholesale price.

As for viscosity, I've rebuilt several 258's with close to 200,000 miles on them that still met OE clearance on the pistons and crank, so OE recommended oil viscosity is best. Your owner's manual gives very good instructions on recommended viscosity based on your local climate, but a 10w-30 or 10w-40 is the best choice for most climates in the U.S.

[Canoe]

How many 4.0L's are running around out there with 200,000 miles or more using regular old cheap house brand API SN 10w-30 with low ZDDP? A lot, and yet we are not hearing of hem eating cams and lifters left and right. So, your 258 is probably fine too. ...

Except mine isn't stock.

... I've got a completely rebuilt 258/4.2 straightened then bored to 4.3, plus a decked 4.0 head (7120) plus stronger valve springs, 4.0 basic header, a wider cam (Baja Beast street legal), high voltage coil & updated ignition module & wires & plugs, and a dizzy that was custom matched to that setup, running Castrol 10W-30 with a ZDDP supplement, along with an offshore MC2150 carb. Somewhere between 20,000 km and 30,000 km on it. So old design with some slightly newer components, but not an old worn engine. ...

I was told by the machinist who rebuilt the engine that with the lobes for the wider cam I MUST use a zinc supplement or an oil that already has that in it. That MUST was reiterated by the mechanic who put the engine back together and into my Eagle. It's only been run with a supplement, and now with the T6.

... That's why I like Rotella T4 10w-30. I have personally sent off samples to laboratories for testing and it tests with 1100 ppm of zinc and 900 ppm of phosphorus. That's not super high, but it's high enough and it's higher than API SN oils. ...

From what I found, those levels should be good for a stock 4.2/4.0. Which Rotella T4 10W-30 did you send for testing? CH-4/SM or CJ-4? Over at bobistheoilguy.com, it warned that back when the CJ-4/SN formulations came out, the updated T4 CJ-4 formulation changed and no longer had that high of zinc and phosphorus, but T6 CJ-4 retained high levels. The recommendation was to change from T4 to T6. If your tested levels are for T4 CJ-4 that would be very interesting.

... I switched over to AMSOIL Z-Rod oil. It's specifically made for classic car engines. I happen to be an AMSOIL dealer, so I get it at wholesale price. ...

Then that's the clear choice for you. For stock engines, and mine with the wider cam, the machinist & mechanic said that such an oil would cover requirements, provided the zinc levels were actually sufficent. I forget the brand of classic car oil they recommended back then if I didn't want to add $ additive with very oil change. But very pricey oil. And crazy pricey in Canada. Over at bobistheoilbuy, most recommendations were for T6 over the classic car oils. It was something to do with better shear if you wanted the max protection.

[Canoe]

People are going to have to shoot this down where I got it wrong...

... OE recommended oil viscosity is best. Your owner's manual gives very good instructions on recommended viscosity based on your local climate, but a 10w-30 or 10w-40 is the best choice for most climates in the U.S.

Modern specs of the oil we can buy today, have the 5W-30 in the TSM not covering the temperature range of where I am. 5W-30 will cover most of my low temperatures, which 10W- will not. And there's a lot of places in the U.S. where the low drops below the 10W- limit of -30 C (-22 F), and in places even below the -35 C (-31 F) limit of 5W-. And that low limit is the Pumpability Max Viscosity - oil will have some flow. With modern oils, the typical viscosity is more interesting.

W grade Cold Cranking Max Viscosity (in mPa∙s), Pumpability Max Viscosity (in mPa∙s), typical @ -30 Cand min Viscosity (in mm²/s) at 100 C :
SAE 15W; max 7000 @ -20 C, max 60,000 @ -25 C (-13 F), min 5.6 @ 100 C
SAE 10W; max 7000 @ -25 C (typical ~4400), max 60,000 @ -30 C (-22 F) (typical ~24,000), min 4.1 @ 100 C
SAE 5W; max 6600 @ -30 C (typical ~3600), max 60,000 @ -35 C (-31 F)(typical ~14,000), min 3.8 @ 100 C
SAE 0W; max 6200 @ -35 C (typical ~8900), max 60,000 @ -40 C (-40 F)(typical ~16,500), min 3.8 @ 100 C
and viscosity on the other end
SAE 30; @ 100 C, min 9.3, max 12.5;
SAE 40; @ 100 C, min 12.5, max 16.3

Those are the limits allowed. It's always interesting to see what actual specs are or aren't published for different products. Wish I had an oil pressure gauge to watch with cold weather startups. And a flow meter would be golden.

Typical viscosity for modern SAEs, @ -45 C, -40 C, -35 C, -30 C, -25 C, 0 C:
10W; ~210,000, ~96,000, ~47,000, ~24,000, ~13,000, ~11,000
5W; ~52,000, ~26,000, ~14,000, ~7,600, ~4,400, ~500
0W; ~33,000, ~16,500, ~8,900, ~5,000, ~3,000, ~375
For the Ws, as temperature drops there's a huge difference in viscosity, hence flow, which is what gets the oil to where it needs to protect.
For the temperatures I will hit, 10W just doesn't offer good oil flow for startup. 5W is significantly better, flowing more at lower temperatures. And 0W does meaningfully better at -30 C and below.

With the "thinner" Ws, there's lower viscosity for more flow when starting.
As the oil warms up, the viscosity is always above the minimum recommended oil viscosity.
Oil temperature is usually within 8 C of the operating temperature (told; don't know if true). With an oil temperature around 190 F to 210 F, the viscosity stays in the teens, with the 40s less thin. A modern oil will maintain its shear when within specified temperatures.With 40 vs. 30, the 40 better resists thinning out if oil temperature goes higher.

I think I may see why vehicles in a warmer climate use a lower coolant thermostat and in cooler climates a warmer thermostat: the engine oil is more likely to be closer to the 195 to 200 F sweet spot?