When recommended oil spec goes thinner

[ZeeOSix]

Originally Posted by AZjeff
Would manufacturers change tolerances in the engine when they spec a thinner oil?


From the engines I've researched, the engine tolorances didn't change when the manufacturer specified a thinner oil. The car manufacturers don't care if the car lasts 250K on 0W-20 vs 300K on 5W-30 for example. All they care about is getting as many CAFE credits as possible.

 

[ZeeOSix]

Originally Posted by AZjeff
Is there any valid mechanical reason to switch an engine that was spec'd to run on 5W-30 to 0W-20? Forget about CAFE.


No, it's CAFE driven. Your engine will have more protection headroom with a 5W-30.

 

[tiger862]

Originally Posted by AZjeff
When I bought the '18 Titan I was surprised to find the oil spec is 0W-20 for the 5.6 DI motor. I was aware that Nissan spec'd 5W-30 for this engine before the '17 new design and DI was added. Would manufacturers change tolerances in the engine when they spec a thinner oil? I'm not afraid of 0W-20 and run it in the RAV on 10k OCIs but have read this 5.6 can be hard on oil. I don't drive hard and not towing right now but it's hot here and it's BITOG...

Engine had several updates along with DI as well as new variable valve system so yes it is different than 2016 engine. Engine has been updated.

 

[dave1251]

Originally Posted by AZjeff
So if an engine is perfectly happy and healthy running on 0/20 instead of 5/30 what does that tell us?

Dave1251, is that Nissan proving grounds to the south of Maricopa or to the east? We see lots of camo'd vehicles making the run to Flagstaff, I work in Camp Verde, they stop there a lot.


Southeast towards Casa Grande.

 

[dave1251]

Originally Posted by ZeeOSix
Originally Posted by AZjeff
Is there any valid mechanical reason to switch an engine that was spec'd to run on 5W-30 to 0W-20? Forget about CAFE.


No, it's CAFE driven. Your engine will have more protection headroom with a 5W-30.


I believe you mean viscosity reserve because if the HTHS is adequate it's still adequate.

 

[ZeeOSix]

Originally Posted by dave1251
Originally Posted by ZeeOSix
Originally Posted by AZjeff
Is there any valid mechanical reason to switch an engine that was spec'd to run on 5W-30 to 0W-20? Forget about CAFE.

No, it's CAFE driven. Your engine will have more protection headroom with a 5W-30.

I believe you mean viscosity reserve because if the HTHS is adequate it's still adequate.


Higher HTHS gives added protection headroom. I'd rather have a bit more HTHS instead of running right on the edge of "adequate" and possible metal-to-metal contact.

 

[bbhero]

Originally Posted by ZeeOSix
Originally Posted by AZjeff
Would manufacturers change tolerances in the engine when they spec a thinner oil?


From the engines I've researched, the engine tolorances didn't change when the manufacturer specified a thinner oil. The car manufacturers don't care if the car lasts 250K on 0W-20 vs 300K on 5W-30 for example. All they care about is getting as many CAFE credits as possible.



Exactly ^^^^^^^^^

 

[Mad_Hatter]

Originally Posted by AZjeff
Is there any valid mechanical reason to switch an engine that was spec'd to run on 5W-30 to 0W-20? Forget about CAFE.

I personally like to use a thicker oil in the event an oil shears and oil film thickness is destroyed, which I would think is a greater potential as the tolerances get tighter on engines (distance between surface asperities), as well as running WOT...A thicker oil gives you more wiggle room in shearing and oil film breakdown, no? But then again the higher quality base stocks of Ow's probably have a naturally higher film strength than 5/10-W's.. maybe that's why 5 and 10w's seem to (me) use more AW/EP additives.🤔