I know it has probly been asked many times, so i tried doing a search and could not pull up anything but 10w30? what do y'all use?? I live in NM where it gets pretty warm as it does cold.

Thank you ! you guys/gals are the best!!

dave....
:shifter:

I use 10-40 Valvoline in my straight eight and have over 100,000 miles on the engine and it runs great

I run 15-40 Delo 400 diesel oil, but I've run 10-30 and straight 30W...they all seemed about the same as far as oil pressure, etc...

thankyou guys!! very much appreciated!!

Hello.
I have a straight 50 oil in my straight eight! =)
Here in Sweden most people driving their American cars just for the summer season, so we dont have to care about coldstarts and things like that.

These engines have very close tolerances so the factory recomended a straight 20 weight oil winter or summer. I thought that would be too thin for summer use but after working at a Buick dealership and rebuilding some of these engines I found the ones that ran 20 weight showed the least amount of wear.

I presently use Delo 15 / 40 made for diesel engines as it contains the proper amount of Zinc needed for these old engines but I have also had good luck with normal automotive oil.

how does the zinc help these engines? Changed the oil today, used 10w30. Its a lot quieter now, but who knows when it was last changed? It was pretty clean.
Thankyou once again for all your opinions.

:thumbsup:

Zinc is a lubricant additive that is formulated to lubricate the Valve Train.

It was removed from oils because it effects the performance of the Catalytic Converter.

Regards,

Tom Gallagher :shield: