Switch to synthetic in 1975 buick 350 engine

[TheTanSedan]

Do a search right here on BITOG

 

[reedsteed2k]

With the 15w-40, is it possible that we'd have trouble starting it in the cold Cleveland winters?

BTW, I went out a bought some SLOB @ the local Big Lots and added to the current oil.

 

[Camu Mahubah]

I have a 1978 Pontiac Gran Prix with the semi-rare 301 V-8. This car has either 86000 or 186000 mi I am not for sure. When I bought it I installed Mobil Drive Clean Synthetic Blend 10w-30. After one month the car was a quart low. The engine did have oil on the bottom so I knew the seals were leaky. Since then I have installed Super Tech HM 10w30 and have topped off with Cenex HM 10w30. Oil consumption is now at one half qt every two months. The ester seal conditoners definitely help a little but I would not expect miracles as older V8s of this vintage may blow by a bit of oil when they are cold.

I have a case of Max Life 10w30 for future oil changes. I have considered running a syn to increase mpg but I didn't want to divy up more for the Max Life synthetic. But if you wanna run synthetic that is the way I would go...