Engine oil weight

[wanderer]

I’m not terribly sophisticated when it comes to this kind of stuff I mean I know how to work on cars and when I was 15 my dad bought me a 57 Plymouth that I had to rebuild from and I’ve put an engine or two in, but usually they were straight and swaps.
And for the life, I can’t understand why anybody would go with zero weight oil I mean, I would think you would want oil coating to stick to the metal parts and keep them lubricated and if I understand this correctly, the zero oil weight does not do that so if somebody please explain all this stuff to me cause I don’t get it

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[Reinen]

The engine tolerances between a modern engine and your 57 Plymouth are night & day. Light years apart. Older engines needed thicker oil, it helped reduce oil consumption in the loose tolerances between engine parts. Modern engines are the opposite. They need thinner oil to get in the much tighter tolerances between engine parts and lubricate them properly.

Modern oil is also very different from '50s oil in many ways other than viscosity. In spite of being thinner, modern oil is much "stickier" than vintage oil. The thinner viscosity doesn't translate to not coating things well, modern oil coats much better. Modern oil also handles the higher temps of modern engines.

This is just the tip of the iceberg, there's a lot more detail to it and people will debate oil endlessly.
But the simple bottom line is that engines have evolved since '57 and so has motor oil. It's an apples to oranges comparison now. What was valid then just doesn't apply anymore. Lower viscosity is part of the modern engine & oil relationship.

 

[Jay Gatsby]

Dude, have you searched for this subject on this forum? There are dozens of threads about oil viscosity. If you’ve got a JL with the 3.6, then you’ve got the PUG (Pentastar Upgrade) which Jeep recommends the 0W-20. Many people have run that oil just fine for 100k miles. Others chose a higher viscosity oil. Supposedly the PUG needs lower viscosity and some say it was designed for it. Others think the recommendation for lower viscosity oil is only for CAFE. Believe what you want and run what you want, it’s your ride. Also many have done UOA on a regular basis and found no wear difference between 0W-20 and a higher viscosity like 5W-30, so there’s that.

 

[azjl#3]

3,,,,,,2,,,,,,,1,,,,,,,

I will add, VVT is not why you use the lower viscosity, and it's the roller bearings in the valve train, not the VVT.

 

[Jay Gatsby]

Here’s a lengthy thread . . .

https://www.jlwranglerforums.com/forum/threads/5w-30-versus-0w-20.152141/

 

[flyer92]

Oh boy...

 

[Terrymo]

 

[Sparky123]

The first time I drained the factory fill 0w-20 oil from our new Nissan Rogue Sport's 2L DI engine, I was shocked how "watery" the oil was. The engine sounded like a sewing machine. Did two short mileage OC's with Idemitsu 0w-20, sounded the same. Third OC. decided to blend 50%/50% 0w-20/5w-30 Pennzoil Ultra Platinum. MUCH quieter and smoother running. IMO, use a "light" 5w-30 oil (such as Ultra Platinum) and your engine and it's little tailpipe will wag w/joy. It really depends on driving conditions/climate. etc, etc....and personal beliefs. (I change out the oil early as well. No long mileage OC's even w/"extended" oils.) If you've been using 0w-20 oil, give 5w-30 oil a try and see/feel if it makes a difference.

 

[Nardulli]

The tolerance idea is not valid. Sorry. I’ve been building engines a long time, and the tolerances for the rotating mass haven’t changed much. I still set them up + 2 Thou not to exceed 2.5 thou. That’s for a 1960’s SBC or a modern 392 Hemi.

OEMs have gone to the 0 W XX oil as a means to fractionally improve fleet fuel mileage. They go on about cold starts blah blah blah but it’s about meeting those fleet numbers. And it is pure stupidity.
VW call for 0-16W . GM was calling for 0W-20 on their 6.2 liter engines. Some DEI hire engineer decided that the oiling holes on their crank journals needs more chamfering. This, together with the 0 weight, has cost GM about $1B - yes, that’s a B. They quietly changed the oil recommendation to 5w30 Dexos. That helps, but they are still seeing oil squirt out of the side of the Bearing instead of staying between the bearing and the journal. The 5 W helps some.

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