15w50 mobile 1, cooler weather, when to change????

[martyb]

I am running 15w50 mobile 1 in my Roe s/c gen 1. Temps are starting to drop here in Chicagoland. At what temperature do I need to think about putting 5w30 back in?? Can I run the 15w50 when the temps are in the 50's???

thanks in advance

marty

 

[carguy07]

The factory fill is 10w-30. I would switch to that if you are due for a change. I doubt that temps in the 50's will hurt anything, synthetic flows so well at any temp. Why are you running that thick in the first place? Are you running it so hard that you feel you need it?

 

[Supercharged Vipermad]

I'll run 15/50 up intil the season is basically over....then I'll do a change to 10/30. I have always run the 15/50 (or 20/50 a LONG time ago) during the HOT months...all on advise from a friend who built race motors, so it is just habit.

 

[Doug Supercharged Vipers]

I'll run 15/50 up intil the season is basically over....then I'll do a change to 10/30. I have always run the 15/50 (or 20/50 a LONG time ago) during the HOT months...all on advise from a friend who built race motors, so it is just habit.

Good choice!

 

[99 R/T 10]

Here's comes a question for "Tom, F&L GoR", but I thought that 15-50 was too thick for engines with low mileage(anything less than 60-70K miles)? Just thinking out loud, but I've always stuck with 10-30.

 

[martyb]

I was also told since I have a s/c car, it would not be a bad idea to run 15-50 during the hot months, and then switch back to 10-30 as the weather cools down.

Does 15-50 break down a bit less when subject to more heat??

thanks for the reply's

marty

 

[GT40DOC]

I plan on running 15w50 Mobil 1 in my engine next summer. It gets soooo hot here and the Viper GTS likes to run hot anyway, I feel that it is safer for my engine.(Just my opinion). I run 20w50 in all of my cars here in So. Az.and my El Camino has 225k on the engine. Our temps don't drop very low around here, but if I lived where the Temps dropped to 35-40F, I would run the 10w30. All of these modern lubricants are so good, that I think that it would be hard to go wrong if you stay with the good ones.

 

[Tom F&L GoR]

A 15W-anything oil should be fine to start a car down to -20C. The SAE J300 tests that determine whether it's a 15W-xx or not are run at -20C and -25C.

The more useful number besides the "50" is the High Temp, High Shear viscosity, which predicts bearing oil film thickness. Generally, bigger is better, but with an increase in "fluid" friction. Consequently you lose a few horsepower or a little fuel economy.

The higher viscosity won't "break down" less, it's just thicker to start with and still thicker when it warms up.

Ideally, a wide split would be best, such as a 10W-50 or 5W-40. Then you get the best of both. All this ignores the contribution of additives, which your engine relies on in the areas like valvetrain parts, rings, and anything that is not pressure fed and hydrodynamic.

I've used mineral oil diesel 15W-40 year round, the synthetic diesel 5W-40 would also be good, as would be Mobil's 0W-40.