Weight of Oil

I would like to know what weight of oil I should put in my grand prix. I have a '99 with a 3.8. I have over 130K on the car. I use the high mileage type of oil but want to know what weight I should use. I have used 10W-40, 10W-30 and even 5W-30 in the winter. With summer around the bend and the miles on the car what weight should I use?

I guess also what does Pontiac recommend to use in the car?

I don't care about the brand or type of oil just the weight.

Thanks

The all around recommended weight is 10W-30. Check your oil filler cap which is the same as specified in the owner's manual.

I agree with Bob. Stay with what is recommended in the owners manual and/or on the oil cap.

i use 10W30 in the summer, and 5W30 in the winter. everyone has opinions. i use lighter weight in the winter cuz where i live...it is COLD!

Nothing wrong with running 5W-30 in the colder months. Makes good common sense depending on where you live. I can see that if you live up North for best fuel economy and cold starting. 10W-30 will cover you to at least zero degrees F or -18 degrees C and if the temperature stays above 60 degrees F. 5W-30 if the temps never get above 60 degrees F. Important part is not to use multi-viscosity oils outside of this weight recommendation or 20W-50. Also, nothing wrong with running synthetic motor oil especially if the temps drop below -20 degrees or all around use. Glad I don't have to worry about it. :grinno: