Stepping down an SAE grade

Here is my reasoning behind using M1 0W40: I have seen thousands of UOAs and testimonials here on Bitog since I joined that formed my thinking of "If an oil is good enough to meet Porsche A40, MB229.3/229.5, VW 502/505, then it should be more than enough to protect ANY of my daily driven cars". The fact that apparently many race teams use M1 0w40, regardless of what oil companies sponsor them, gives me piece of mind with that oil choice. I don't have the ability and resources to rebuild and remeasure my engine internals every few weeks, so I'll rely on the oil choice of those who do just that between races. Cheap insurance, so to say. Yes, daily driver is not a racecar, but still.

Here is the reason for this thread: I gave my friend plenty of reasons and examples behind why I am using M1 0W40 in all my vehicles, but he had a hard time explaining his reasoning behind why all cars should switch to 0w20. His main points were:
- It flows better when cold.
- Nearly all manufacturers switched to 0w20, so all cars made in the last 25 years have no reason not to use 0w20 as well.
Neither of his points were convincing enough, so I turned to the biggest oil forum to see if anyone shares and exercises the views of my friend, and could provide more convincing reasons, or factual proof, of why 0W20 grade is superior and should be used across the board.

Your buddy's logic is a big flaccid.

- It flows better when cold
This is primarily only beneficial for fuel economy. A thinner oil starts thinner so for that first bit of warm-up you are using less fuel. This is not by an earth shattering amount, but it matters to CAFE and across millions of vehicles, is significant. There is no other benefit as long as you are using a lubricant with the appropriate Winter rating for your climate.

- Nearly all manufacturers switched to 0w20, so all cars made in the last 25 years have no reason not to use 0w20 as well.
They all switched to it because of the CAFE credits they receive from it in the USA and this naturally spread to other markets. The Japanese have also been chasing incremental fuel efficiency gains in their home market, hence the experimentation with even thinner grades like 0w-12, 0w-8...etc.

This in no way implies that an engine that spec's 5w-30 for example is well suited to run on 0w-20. There are numerous changes that may be necessary to allow an engine to run on thinner lubricants. Some of these things are higher volume oil pumps, wider bearings/journals and different surface coatings. This is why when Ford was back-spec'ing many of their engines to 5w-20 there were some that were notably excluded.

On the other hand, many high performance applications spec 0w-40 or a heavier oil, even if their more pedestrian sibling spec's a lighter oil. The example of the Mustang GT "Track Pack" is often brought up, being identical to the "regular" GT that spec'd 5w-20, but in the case of the Track Pack, spec'd 5w-50. The 6.4L HEMI, which shares a whole host of parts and dimensions with the 5.7L spec's 0w-40 instead of the 5.7L's 5w-20.

While there is essentially zero risk going up a grade or two as long as the appropriate Winter rating is observed, the same cannot be said for going down a grade or two where the possibility of wiping a rod bearing may exist for example if the engine design lacks sufficient margin in that area.
 
If an Enzo can survive 0W-20 I bet most cars could survive 0W-16.

I remember following those experiments of AEHaas.

It's all about oil temperature. He doesn't track his cars and they have massive sumps. For tooling around town in them and never seeing WOT, the inherent risk is quite low. If he were to take them to Sebring and lap them, he might find his car deciding to play a game of rod "peek-a-boo".
 
I have a absolutely beautiful 94 ford conversion van bought 3 years ago with 19,800 miles. Sitting at 33,000 now.
When I bought it I wanted the best so started looking up recommended grades and so on. Looked on Amsoil sight they was recommending 0w20?? or may have been 5w20. I was wondering why then checked what ford is recommending which was the same 20 weight while my manual and oil cap show 5w30. Manual also adds 10/30 as well for cooler weather. This totally made me question everything about manufacturers recommendations. If the engine was originally designed for 10w30 why have they now switched saying my engine should run this 0w20? I ended up choosing exactly what the OP is switching his vehicles to which is mobile 1 0w40 euro blend. What led me to this is the 5.8l engine up until 94 was a flat tappet design but some of the vans did not get the new roller setup until 95. Pretty sure mine is the roller setup but I chose a oil I figured would work for both. Loving it so far.

When Ford went 5W-20 they went back and tested their previous designs. The ones that did well with it they recommended it for. The ones that didn't (4.0 OHC) they continued to recommend 5W-30. In the era the recommendations were made the Motorcraft 5W-20 was more shear stable and the 5W-30 Conventional would shear to a 20 Grade. Why have possible sludge precursors if you don't need to? This is also why GM and Dodge went back to 10W-30 except in low temps for a while.

My usual suggestion at the time was 10W-30 or 5W-30 Synthetic. If you wanted a budget oil and needed 5W go with MC 5W-20 Blend and don't look back (at the time it was competitively priced with conventional) as it was a better over all oil. If you had a problem child you would just have to suck it up and pay the freight for 5W-30 Synthetic.
 
I ran 10W-30 Rotella/Delo/Delvac in HD Engines that speced 15W-40 for millions of miles on dedicated light freight in relatively flat country. You don't need oil speced for 235F oil temps when the oil never exceeds 190F.

I also have rub75W-90 in axles that speced 85W-140 for millions of miles.

This was all done with the approval of the engine and axle manufacturers.

PS Most people like to point out Australia often specs higher grade oils. At the time the axle manufacturer speced 85W-140 USA and 75W-90 in Australia. Odd don't you think?
 
It's all about oil temperature. He doesn't track his cars and they have massive sumps. For tooling around town in them and never seeing WOT, the inherent risk is quite low. If he were to take them to Sebring and lap them, he might find his car deciding to play a game of rod "peek-a-boo".

This I agree with which this which is why I don't run 5W-50 in my Mustang on the street. It's was in the car from factory because the standard cars have a 120C Derate and the Track Packs are 150C. Don't really see the point of 5W-50 with an oil cooler on the street.

Didn't think of that when the OP posted.

2014 Mustang 5.0 Track Pack
Recommended Oil - 5W50

2014 Mustang 5.0 Track Pack w/ Roush Supercharger Street Oil - 10W30
 
Which is also much of the reason for the regional differentiation beyond so much CAFE everywhere. Just as US cars for ages were regarded as not in the least autobahntauglich because of little oil-coiling etc. Better cover whole of Europe with one thicker grade for everything sold over here than have one guy one summer make one car with high beams lit glow stuck on one prominent left lane of Germany for giving it all at hundreds of km/h. Untimely fears to overcome. By speed limit one day and meanwhile by heavy oil.

More interesting than flooding AntiCAFE could be some consideration, how much worse the cars really fare in the US while still on factory warranty oil. And the question, what became of names that obeyed to the CAFE international right over the Autobahn, letting fly on 0W-20 films. Their dealers are still around. Somehow they're still deemed autobahntauglich.

Well, let's at least be on watch for entertaining activism stepping down one or two grades as Vladiator asked for, perhaps.
 
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I ran 20 grade oils in the Enzo that is spec'ed for 10W-60 but I did not drive on the race track at 225 MPH either, I drove around town. I ran 20 grade oils in my Maranello 575, my Rolls Royce Ghost, Bentley Flying Spur Speed with better then average used oil tests. I had a neighbor with an Enzo. We drove the same places and the same way. My oil test wear metals were 1/4 of his running the much thicker oil. Too thick can increase wear.

Currently I have a Lincoln Navigator that specs 5W-30 and I am running a 20 grade oil. Though it is hot here in Florida I am not towing 10,000 lbs up 5 mile hills in Virginia nor Arizona at 90 MPH. Most specifications are for worst case heat and load situations and fuel diluted oils. Sans these issues you are likely safe with a grade or even two lower grade oil. But the absolute test is the use of a true oil pressure gauge. This will tell you if you are safe with whatever grade you choose.

I would be comfortable with 10 PSI oil pressure per 1,000 RPM. I ran Mobil One 0W-20 in the Maranello and had more pressure than this with good oil analysis reports.

AEHaas
 
Well, much of the pressure discussion is just how hydraulics work. Major impacts are ID, flow rate, length, etc …
Viscosity (just to compare one grade to the next) has a minor effect on residual pressure …
 
AEHass


Same here.

Caterham and AEhass used to say you could do it , if you had a real oil pressure gauge, and observed that at full temp. Not a idiot type gauge. They claim as long as you have acceptable oil pressure at full operating temp, its ok.
I would not recommend it, too little return/advantage for the risk.
I would also NOT recommend it. That advice ignores the required min. film thickness to support a bearing and also the piston skirt with high side thrust loads; also some engine still run direct DOHC with bucket tappets.
Oil pressure puts oil into the bearing - it does NOT support the bearing under high loading! Once you are at Op Temp,
you are at the mercy of HTHS and its OFT.
2.6cp is not 3.2cp.

Ken
 
When Ford went 5W-20 they went back and tested their previous designs. The ones that did well with it they recommended it for.
....

Like in the 1950's with the Y block. Photo of Ford Oil Grade Recommendation sticker on an unrestored car:
Ford_Y_block oil  requirement sticker..jpg
 
I wouldn't do it. Going up, yes,as is always mentioned in FSM's for severe operating conditions, but I've never seen a recommendation for running thinner, but have seen many warnings about doing so.

THIS ^^^

With all the CAFE mandates, the mfg's are already using the thinnest oils they can get away with without ruining engines and resulting in waranty issues for them. Why anyone would purposely want to run thinner oils than the already thin CAFE oils is beyond me.
 
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I wouldn't do it. Going up, yes,as is always mentioned in FSM's for severe operating conditions, but I've never seen a recommendation for running thinner, but have seen many warnings about doing so.
I would not recommend it, too little return/advantage for the risk.
These summarize my thoughts well. Many engines including my Tacoma 2TR-FE have seen updated specs, going from 5w30 in my 2006 truck to 0w20 for newer models with the same engine. I just don't see why Toyota would re-engineer such a good engine to run "better" on 0w20 vs the original 5w30 spec, and based on other discussions, I've concluded the upgraded spec is based on CAFE. Yes a little better MPG is appealing, but I have no reason to believe 0w20 is flowing significantly better in my climate, and certainly would not protect better than 5w30.
 
Caterham and AEhass used to say you could do it , if you had a real oil pressure gauge, and observed that at full temp. Not a idiot type gauge. They claim as long as you have acceptable oil pressue at full operating temp, its ok.

Who's to say what the minimum "acceptable oil pressure" should be at full operating temperature to prevent excessive engine wear (ie, inadequate MOFT)?

Oil pressure will decrease as viscosity and HTHS decreases from decreased viscosity and oil temperature. MOFT also decreases with decreased viscosity & HTHS.
 
This I agree with which this which is why I don't run 5W-50 in my Mustang on the street. It's was in the car from factory because the standard cars have a 120C Derate and the Track Packs are 150C. Don't really see the point of 5W-50 with an oil cooler on the street.

Didn't think of that when the OP posted.

2014 Mustang 5.0 Track Pack
Recommended Oil - 5W50

2014 Mustang 5.0 Track Pack w/ Roush Supercharger Street Oil - 10W30

Mustang GT350 with the VooDoo has 5W-50 on the oil fill cap.
 
Who's to say what the minimum "acceptable oil pressure" should be at full operating temperature to prevent excessive engine wear (ie, inadequate MOFT)?

Oil pressure will decrease as viscosity and HTHS decreases from decreased viscosity and oil temperature. MOFT also decreases with decreased viscosity & HTHS.

I agree, I'm a thickie!
 
Couldn't there be this one thread not turned into an ungraded thickie disposal? I'm striking through: immediately, but still...
 
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