SnappyPappy

Please explain what you mean by 'thin' oils? What are you currently using? I'm at that juncture where I need to decide on what to change to. I'm considering 5/30 Mobil-1. I would get 5/20 but can't find it.

SodaLuvr

Viscosity difference between the Mobil 1 0W20 and the 5W/30 WAS +/- 5%, so it wasn't a significant difference. Haven't seen a VOA of the new 5W/20 yet, so I don't know for sure. It should be about the same.

Road Rage

Umm, let's be precise in our paraphrasing. I never said "thicker is better", or would have recommended a 15w50 or a 10w60. I also have recommended 5w20 more than once on this Forum. So I think referring to me specifically as part of a "crowd" supporting thicker is better is out of context.

I receive many PM's, and a lot of them are from people in the Southeast or Southwest, inquiring whether a one size fits all viscosity of 5w20 is optimum for their driving environments and styles.

I did say in several different posts that 10w30 synoil has no downside in this engine, provides a stronger film strength at high temps, high RPM, and high loads; resists shear better, is still available in SL spec formulations, and has a proven track record of providing good economy and outstanding protection. 5w20's and thinner oils miss on all or most of these criteria - for my money, I want to see if the thinoils prove themselves before I recommend them unconditionally. In scouring the reasons for going to 5w20 and thinner, I have yet to find one mfr that states they did it to reduce wear - it is always associated with fuel economy reduced emissions, or in the Company's best interest to help them with CAFE, allowing sales of highly profitable vehicles like SUV's.

I also find it interesting that most, if not all, high performance European sports sedans use 5w40.

SodaLuvr

I don’t disagree that 5W/20 is now used in Fords, Hondas, Dodges, and Chryslers because of the increased CAFÉ.

Yes, the SL formulations look “stronger” than the SM formulations, but the base oils have been improved in the new SM flavors. Also, I’d like to note that some manufacturers have started putting Antimony and/or Sodium in the oils; it’d be interesting to see how those oils perform once the UOAs start pouring in.

In the case of the M1, I don’t disagree that the 10W/30 is more shear stable. However, in petroleum oils, I’ve noticed that sometimes 5W/20 are more shear stable than 5W/30 oils, in some brands of dino. I can’t recall the brand at the moment though.

A track record doesn’t impress me completely. I instead, rather see oil analysis results for this engine from the usage of both, and instead compare the wear. That is the most accurate way of determining the better oil for this engine. Keep in mind that in the case of M1 10W/30 versus M1 0W/20, the viscosity difference is less than 5%, not enough to make much of a difference. However, the 10W/30 is technically more shear stable, but the many reports that I’ve seen of 0W/20 shows that it is perfectly shear stable, even when the engine is used hard. Thus, I know that M1 0W/20 does not have a problem with shearing. 5W/20 does not increase wear; the wear is almost always just as good as a 30wt.

If you want proof that thin oils work well, I’d suggest that you head over to Bobistheoilguy and do a search for UOAs on 20wts. The majority of them are Mazdas, and you’ll find that sometimes a 20wt actually offered better wear than a 30wt in a 3.0L Duratech engine. Now that was impressive to me.

Just keep in mind RR that, letting 5W/20 oils in general prove themselves is a good thing, but it’s better for them to prove themselves in this particular engine, since that is what we’re here for, right? I’d be interested in seeing a comparison of 5W/20 and 10W/30 in this engine. I’m willing to bet that if the test is conducted when the engine is well-broken into, say with 60,000 miles, that the 5W/20 will have just as good wear but possibly increased fuel economy.

In the end, I’d rather use the thinnest oil that will offer me the best wear. JetJock should have an UOA coming soon with a short run on Redline 5W/20 and a M1 M-110 filter, however, that won’t tell much since there are still a lot of wear metals remaining from the break-in period.

Michael

Legend2TL

Besides increased CAFE, the other obvious benefit of thinner oil is increased engine power through less oil pumping losses.

Repecat

I would be very curious as to how much additional horsepower is required to pump 30 wt oil as opposed to 20 wt. Of course, additional friction losses would be part of the equation.

Legend2TL

I'd be curious also to see what a dyno run would be for 5W-20 versus 10W-30. I suspect it would be measuable, racing teams from F1 to NASCAR typically check the conditions of the engine environment and run as thin an oil as possible. They're concerned about wear also but naturally the engine life is measured in single digit hours but they still have to finish.

The increasing accuracy of CNC tooling has allowed more uniform and smaller
tolerances in internal engine parts, in some causes running a 10W-30 may cause more startup wear due to the tighter oil passages and bearing clearances in today's engines.

I had a conversation a long time ago with a Honda motorcycle factory represenative concerning cam wear problems I was having on my bike. He was fairly open and sincere about my problem, I remember him instructing me to use the year round 10W-40 range oil and not the 20W-50 (which could be used in summer months with higher temperature accordning to the owners manual). He pointed out the tight bearing clearances cause far more engine wear at startup for the 20W-50 weight versus the high RPM wear for the 10W-40 which he felt was the probably the same for either weight oil.