Changing Oil Viscosity

[cdalton]

I have a new 2003 w/V8 and I pull a boat (23 foot runabout) in the summer for 3 hour trips out of overdrive (high rpm's). I am contemplating changing to Mobil 1 10W30 for this reason in the summer and then changing back to 5W30 in winter. Does anybody know if it is a problem switching viscosities or should I just stick to 10W30 year round. I'm in Indianapolis and it gets down to 0 degrees but not often. Also I think 5W30 is to light of oil for a V8 anyway even without towing. Anybody have any advice?

[Stooge]

I would always run the 10W30. Gas mileage differences are nil but the wear is probably less with the thicker oil.

[KLS]

Both oils are 30 wt @ 100°C...but, the 5W-30 may be more prone to losing viscosity through a process know as shearing. The "viscosity index improver" polymers get mechanically damaged and the result is lower viscosity after a couple of thousand miles. I'd stick to 10W-30 in the summer. There is no problem with changing viscosity as the climate changes. In fact, it is a very good idea. With your hot summers and the weight of your boat, do consider using an API-SL 15W-40 oil, even though it's not listed in your owner's manual.

Mobil 1 is a thin 30 wt. The range for 30 wt. is 9.3 to 12.4 cSt @ 100°C (http://www.chevron.com/prodserv/NewO...y_motoroil.htm ) and Mobil 1 comes in on the low side (https://dallnd6.dal.mobil.com/GIS/Mo...0?OpenDocument )

Mobil 1 is an excellent oil. If you can find a retail source for Schaeffer #703 10W-30 or #700 15W-40 in your area ((800) 325-9962), you'll find that it's cheaper and gives equal protection as M 1.
http://www.schaefferoil.com/data/703.htm
http://www.schaefferoil.com/data/700.htm

In some ways, the Schaeffer oil may give better protection. The Mobil 1 xW-30 carries the European rating of ACEA A1 (lowest) and the Schaeffer xW-30 carries the rating of A3 (highest) especially with better High Temperature/High Shear ratings.
http://www.acea.be/ACEA/20020618Publ...lSequences.pdf Page 4 &5


Ken

[SATundra]

I run the Mobil 1 5W-30 in the winter, and the 10W-30 in the summer here.

You 've got an '03 so im not sure that you have the tranny cooler mounted in front of the radiator or not. If you don't you might be better off running EITHER oil and adding that extra tranny cooler.

[acme]

Originally posted by SATundra
I run the Mobil 1 5W-30 in the winter, and the 10W-30 in the summer here.

You 've got an '03 so im not sure that you have the tranny cooler mounted in front of the radiator or not. If you don't you might be better off running EITHER oil and adding that extra tranny cooler.

I run 0-40 Mobil 1 . It can be used in place of 0-30 or 5-30 and is rated " Energy Conserving" and withstands high shear and heat in the summer. Also ok for winter.

From Mobil 1 :

..Mobil 1 with SuperSynTM 0W-40 is formulated for newer European cars, especially those with advanced-technology, multi-valve engines. It can be used where an SAE 0W-40, 0W-30, 5W-30 or 5W-40 grade viscosity is recommended.
alan