Thin motor oil, does it really save gas?
 

There's a lively discussion over on BobIsTheOilGuy about the benefits of 0W20 and similar 'fuel saving' oils. Has anyone here switched from a thicker oil (5/10W30/40) to a 'thin' (0/5W20) lube? Did you see a significant change in FE? Do you happen to have fuel log data? (Not a matter of trust, I'd just like to see the numbers! :) )

Thanks!

I can't say anything for mileage but going from 10w30 to 0w20 did make my old Tracker feel a little better when it was cold. I am talking about mornings in the teens and twentys tho.

i would not sacrifice lubrication for a miniscule economy gain. just use a 0W30 to be safe.

Some cars have been "cleared" for 5W20 from originally specced 5W30 though. I think Ford released a TSB saying most everything from the mid 90s up was okay with 5W20 if 5W30 was originally specified.

Don't whatever you do start running 20W50 for oil consumption problems, been there, go to a 5W30 "high mileage" oil, I found Pennzoil, and Castrol to be the best in Marvin (Motomaster isn't too bad either if you're in Canada)

Changing from 5W40 (I'm pretty sure that's what was in it) to 0W30 in Effram didn't produce measurable improvements. 09/03/2008 is the date of the gaslog entry for that oil change.

actual testing, do a web search, will result up to . 5 mpg better.
I run 5w20 in my '99 dakota 4x4 w/ 5.2 L v-8 in the winter time, oil analysis came back nothing unusal. The engine does rev faster when that oil is in there. warmer temps I run 5w30.

checkout this write up. The author does post on bobistheoilguy.
https://www.toyotatundraforum.com/tec...oil-101-a.html

this site has some decent info
https://machinerylubrication.com/

what ever oil u use, recommend an oil analysis, its the only way to know, if u read BITOG, then u already know that.
good luck

Thanks guys.
The thread in question is at: https://www.bobistheoilguy.com/forums...Number=1526919 Feel free to wade in.... :)

I'm with you in that regard. While the xW20 oils are well proven, I'm an old fart and am somewhat suspicious of the CAFE enforced spec. Hydrodynamic bearings require viscosity to generate pressure, and I don't see the point in running anywhere near the edge of the envelope. I do a lot of P/G, and the engine sees lots of idling in neutral and low RPM, moderate throttle use. Under those conditions, my thinking is that somewhat thicker oil will work better. Furthermore, the drag difference between 'thick' and 'thin' oil at low revs is minimal.

I've read that 15w40 is best for lubrication and fuel economy. If it is best for lubrication it would make sense that it is best for fuel economy, because of less friction. I use 10w40 year round.

I use 0w30 in my cav. I haven't seen any gains from it. The main reason I use it, is it is the only oil I can run for 8000 miles before changing. Even at 8k, it still has a TSB of ~3.