My mechanic put 20w-50 in my car.

Status
Not open for further replies.
Joined
Mar 4, 2007
Messages
69
Location
Alabama
It's a 94 camaro v8. A shadetree mechanic put a used engine with 160000 miles in my car. He filled it with Castrol GTX 20w-50. I think that is too thick and would like to try a thinner oil like 5w-30 since that is what is speced for my car.

I don't want to waste this oil so would it do any harm to leave it in for 3-5000 miles?
 
In 'bama, in the Summer, it'll be fine...

If past OCI are unknown keep a eye on the level and color of the oil, if it gets dark early, you want to consider this oil a flush and do another change in 1.5-2Kmi...
 
Originally Posted By: vincent714028
It's a 94 camaro v8. A shadetree mechanic put a used engine with 160000 miles in my car. He filled it with Castrol GTX 20w-50. I think that is too thick and would like to try a thinner oil like 5w-30 since that is what is speced for my car.

I don't want to waste this oil so would it do any harm to leave it in for 3-5000 miles?


No reason for that heavy of an oil in that motor,period.
 
20W-50 in a GM 8 cylinder with 160 K miles is a good summer oil. It might cost you a little in MPG's, but with 160 K miles any XW-30 oil is probably too thin. Often when you get that kind of miles on a old GM 8 cylinder you have to use a 40 or a 50 grade as the top number.

I have Castrol GTX 20W-50 in my 1985 Olds Delts 88 with over 160 K miles on it. I had to go to something thicker than a XW-30 because it burned and leaked 30 too fast, and it would sometimes stall on a very hot day. With the 20W-50 I do not have to add oil as often, and I do not have to smell the leaking oil burning off, and it does not stall on hot days.

With that kink of miles the clearance between parts is more than it was when new, and a thicker oil works better.

I am thinking of going with something like the newer 5W-50 oil for winter. Right now with a 20W-50 in it, 15 Fahrenheit is about the coldest that I would have the temperature be and still try to start it.
 
Find a new mechanic...

The only time that motor NEEDS 20w50 is under long track sessions, but seeing as it is already in there I would run it out for a few thousand miles though, then change to 5w30.
 
Ask him WHY he proberbly paid more and put in a non mainstream oil like
20 w-50?

It won't do any harm, even in Canada, I once used this oil, year round, in a Toyota truck
And got very long engine life.

But the only reason why I think he might use it, is because he suspects the engine may be an oil burner.
 
Originally Posted By: vincent714028
It's a 94 camaro v8. A shadetree mechanic put a used engine with 160000 miles in my car. He filled it with Castrol GTX 20w-50. I think that is too thick and would like to try a thinner oil like 5w-30 since that is what is speced for my car.

I don't want to waste this oil so would it do any harm to leave it in for 3-5000 miles?


When you say specced for do you mean whats on the oil cap or dip stick? Thats a base recommended for all seasons. Take a look in your manual. What does it recommend for oil when temps are (for example) + 20 F?

Something like this?
oil_chart.jpg


I agree its not the best choice but it wont hurt it to leave it in and get your moneys worth. Does it burn any oil? Just blend it down topping off with some thinner oil.
 
You can drain out half the oil and save it for next OCI, then refill the half with 5w20. Will end up with somewhere in the upper end of the ballpark of 10w40.
 
Originally Posted By: TallPaul
Hope he is not trying to cover up loose fitting bearings. But 20w50 should be no problem in Alabama in the summer.


I was thinking that as well.
 
Originally Posted By: daves87rs
Originally Posted By: TallPaul
Hope he is not trying to cover up loose fitting bearings. But 20w50 should be no problem in Alabama in the summer.


I was thinking that as well.


I was thinking the same too.

In fairness to the mechanic though, OP said he was only fitting a used engine, and sometimes you just don't know for sure how an engine really is until it's in and running. Being Alabama and summer, he's probably just being a bit cautious given there could be some degree of uncertainty about the engines exact condition.

OP, I'd leave it at least over summer, and keep track of any oil consumption during that time.
 
Last edited:
Originally Posted By: TallPaul
You can drain out half the oil and save it for next OCI, then refill the half with 5w20. Will end up with somewhere in the upper end of the ballpark of 10w40.


Lot of work to save 4 bucks:)
 
Originally Posted By: vincent714028
It's a 94 camaro v8. A shadetree mechanic put a used engine with 160000 miles in my car. He filled it with Castrol GTX 20w-50. I think that is too thick and would like to try a thinner oil like 5w-30 since that is what is speced for my car.

I don't want to waste this oil so would it do any harm to leave it in for 3-5000 miles?


Why all the worry about the oil? I'd be much concerned about a used engine with 160K. That would be a LT1 engine, right? It's a good design but who knows how it was treated?
 
Last edited:
I run 20/50 in my 83 Silverado with the 305 during the summer months with no problems
cheers3.gif
 
Status
Not open for further replies.
Back
Top