I was told by the machanic who changed the engine in my 1999 grand am to use 20/50 instead of the recommended 5/30 oil my car has 134000 miles and ran great till I got the engine changed! Help Please I don’t think its a good idea to put 20/50 oil!!
I Agree. I Don’t Think It’s A Good Idea. Sometimes People Do This In Order To Avoid Repairing An Engine Or Replacing An Engine That Has Excessively High Oil Consumption.
CSA
Why did the mechanic say it should have 20/50? Have you had to add oil on a regular bases or is he suggesting any car with 134,000 miles needs heavier oil? Is you car used in some unusual way?
I would not follow his advice without a explanation.Where do you live? Perhaps this is OK for southern FL, but not a good idea if you live in Buffalo NY.
I live in nyc
While NYC isn’t the coldest place in the US…it does see it’s share of cold weather. 20/50 is NOT a good idea from November thru April in NYC. At 30 degrees 20w oil is like molasses.
20/50 oil in this engine is not a good idea unless you live in a dessert with 120 degrees being the norm. If you can’t run the OEM reccommended weight oil in that engine without smoking/knocking, then the engine has problems.
It sounds like your “mechanic” sold you a very worn engine that would consume oil if 5W30 was put in.
Agree with others that 5W30 is the right oil for New York City. In the tropics, such as Hawaii, South Florida, and the San Diego areas you can use 20W50 provided you do not leave those areas.
At that weight, you should save yourself the hassle of even worrying about oil, just buy a big jug of molasses syrup and pour in, it’ll be about the same consistency. 
I can remember when Honda moved 5 “points” (I guess you call them points) in viscosity rating for what to put in certain vehicles. It was a move from 5/20 to 10/20 or 10 to 5 ,some very minor move, and management was on us hard to use the right oil in the right car. Now a move from 5/30 to 20/50 that is quite a move, and one that needs an explaination.
If your engine was running great, why did you need to change it?
Or do you actually mean that you had the oil changed, and now the engine doesn’t run as good anymore?
Engines don’t need to be changed unless they are running bad.
I can’t tell if you changed the engine, or just the engine oil.
If you mean that the oil was changed, and now the engine doesn’t feel as good, then you need to take your car to a different shop, and have the oil changed to the proper oil for it.
BC.
That’s an old sheister used car lot trick to quiet noisy engines.
If yours can’t use the correct oil, there’s something wrong with it…
…and your mechanic.
Using 20/50 oil will not hurt anything unless it’s used in very cold weather with short trips involved, etc.
The comment about covering up engine problems with 20/50 is correct but should have nothing to do with how the engine actually performs.
I do have a question or two though. If the car ran great then why did you have the engine changed?
Or do you mean it ran great until the oil was changed?