First time changing the oil

[Norsky4360]

Not knowing when the oil was last changed on "The Beast" and not having any documentation on the car (owner's manual, service records, etc) I have a "rookie" question to ask.

I went to my local NAPA store today to get a list of things and had to ask what grade (and how many quarts) of oil to use. Full synthetic was the obvious answer and the NAPA guy also told me 10W-30. When I got home and popped the hood the oil cap reads 5W-30.

This car is not going to see much, if any, cold weather operation so what grade oil should I use?

[Wegone]

9 Quarts let it drain 2 hours...I use 10w30..Mobil 1 Full synthetic, I'm sure 90 & 91 came with Dino-oil not that I would use it..

Just got home and checked my 91 says 10w30, Im not sure when they started using Full synthetic maybe 92 or 93...maybe someone has changed your oil fill cap?

[Hib Halverson]

Ignore what's on the oil cap. In fact, if the car's a 90 and the cap says 5w30, that's the wrong cap. 90-92 LT5 engines took a 10W30 petroleum-based oil. The 93-95s used a factory-fill 5W30 Mobil 1.

So, your engine either has a 93-95 oil cap or an oil cap from some other engine that takes 5W30.

Bottom line: ignore any advice to use a 5W30 in the LT5. Use a 10W30 synthetic. Mobil 1 is good. Red Line is better.

[Norsky4360]

There are little things with this car, like this oil cap difference, that are making me wonder if the previous owner is really as serious a car guy as I was told he is.

The majority of the replies I've gotten to the same question posted on CF seem to point to 10W-30 as well. Oil choices by folks over there range from it's ok to use 5W-30 up to 15W-50.

I fully intended to use synthetic oil but just wanted to be sure of the currect viscosity.

Thanks!

[Aurora40]

Originally Posted by Norsky4360

There are little things with this car, like this oil cap difference, that are making me wonder if the previous owner is really as serious a car guy as I was told he is.

Well, I wouldn't take the wrong cap as a sign of abuse or neglect or anything. Maybe that's what a dealer sold him, maybe that's the only one he could get in a pinch, etc. As long as it performs the function of keeping oil in the engine and crud out, it doesn't seem like too big a deal.

[Rob]

Originally Posted by Hib Halverson

Ignore what's on the oil cap. In fact, if the car's a 90 and the cap says 5w30, that's the wrong cap. 90-92 LT5 engines took a 10W30 petroleum-based oil. The 93-95s used a factory-fill 5W30 Mobil 1.

So, your engine either has a 93-95 oil cap or an oil cap from some other engine that takes 5W30.

Bottom line: ignore any advice to use a 5W30 in the LT5. Use a 10W30 synthetic. Mobil 1 is good. Red Line is better.

I agree with Hib, 100%.

I have used Mobil 1 Synthetic 10W30 in my '90 since I bought it in '94.