oil viscosity compatibility

[William F.]

In changeing oil in my '67, I first added a gal jug of Rotella T 10W30. I can buy 15W40 but not 10W30 in quart size. Will there be a problem if I use the qt of 15W40 to give the 5 qt total?
Thanks

[Jimmy G.]

Re: oil viscosity compatibility

NO Will change the overall viscosity but should be no problem. Odd that Shell sells a gallon container of some and not quarts of all. I have that same issue when I change oil as well.

[Mark E.]

Re: oil viscosity compatibility

I buy the gallons and just always have a partial container on the shelf. It's a bit cheaper in the long run if you have the space. But as Jimmy says, mixing viscosity isn't an issue.

[Leif A.]

Re: oil viscosity compatibility

Why not simply run five quarts of 15w40?

[William F.]

Re: oil viscosity compatibility

Still would have to buy additional qt unless you bought 2 gal jugs. Also, maybe being OC, but 15-40 was not on recommended list in original manual but I know a lot use it since easier to find.