Proper Oil Weight For '87 GM

[miamibob]

Have seen various specs for this. 10W30 or 10W40 being the most popular. I am in South East Florida (which lately has seen colder winters) so what are your thoughts??? MB

[1990LTD]

10w30

[johnunit]

you will be completely fine with either. I ran 15w40 in my crown vic last winter in Canada, lots of sub-zero starts, and the oil weight never seemed to affect it.

If anything, go with the slightly thicker oil if you have some sort of tap/knock, and lower weight oil if you're obsessed with fuel economy.

I live in an area that sees 90 degrees or even more in the summer and well below 0F in the winter, and wouldn't even stop to think about the difference between those two oil weights.

[1990LTD]

I tried 5w30 in the winter and it made little difference.

[Southern_Pride]

I run 15w40 and I'm within 200 miles of you.

[Lincolnmania]

i would use 10w30 in the wintertime and 10w40 in the summertime

[miamibob]

Just looked at the original manual and the preferred weight is 5W30 or perhaps 10W30 (warmer climates??). Who knew! I would have guessed 10W40 or maybe 10W30 but not 5W30. Probably looking at better MPG's!

[gadget73]

With an older, looser motor I would be a bit concerned about running 5w30. If you have good oil pressure with the motor warmed up, you're probably fine but a lot of these things barely make oil pressure when the motor is hot.

[Crownvicman289]

I run synthetic in the truck, and will do so on the Crown Vic when I do the Exploder swap when I get back home. The truck has 200,000 on it so it gets 0W40. There's a couple reasons: a 5W oil, when it's freezing balls outside, only flows like a 5W oil would flow at said freezing balls, so it's still molasses. 0W flows a little better than that, and as soon as it warms up it starts flowing like a 40W would at that temperature. Furthermore, when a synthetic oil breaks down, it reverts to the heavier weight unlike dyno oil that reverts to its lower weight. I'll probably run 0W30 in the Crown Vic, that way I can run the same thing year-round. Isn't there some myth that running the same oil all the time is good for your engine?

[gadget73]

I think that has to do with the idea that different brands of oils have different additives, and they may not be compatible or something. Not quite sure I buy all that, but most of the time I end up running Walmart synthetic oil because I'm a cheapass but I still want fake oil and they happen to have the best price. I really think that changing the oil regularly has a lot more to do with being good for the motor than running a certain brand or weight of oil all the time does.

[Crownvicman289]

I really think that changing the oil regularly has a lot more to do with being good for the motor than running a certain brand or weight of oil all the time does.

I agree 100%, the only reason I justify synthetic is because on dino oil I change every 3k and syn I change every 5k. The cost per oil change breaks even like this, so all I really get is less work and some peace of mind which might be total bullshit.