Changing/Flushing Bad Oil

[nelsongg]

A friend of mine just picked up a used boat with a 5.7 VP in it. He isn't sure when the last time the oil was changed, but he said that it looks like it has been awhile.
He wants to make sure he flushes the maximum amount of contaminants out of the engine before the winter layup. His idea is to remove the existing oil and refill it with a cheap dino oil. Run it on muffs for a while, then drain that oil. And finally, put in synthetic (which is what he plans on using here on out) before storage.

His question to me (and now to you since I wasn't sure) is it worth it to run the clean dino oil through to clean remaining contaminants in the engine? And also, if it is a bad thing to put the dino oil through the engine and then change to synthetic?

Thanks,
Greg

 

[doyall]

Re: Changing/Flushing Bad Oil

... His question to me (and now to you since I wasn't sure) is it worth it to run the clean dino oil through to clean remaining contaminants in the engine? And also, if it is a bad thing to put the dino oil through the engine and then change to synthetic? ...

Although it probably wasn't necessary, I did the same thing to a 5.0L I purchased two years ago as it appeared the prior owner didn't appear to be too vigilant about routine maintenance. It made me 'feel' better. It probably will be the same situation for your friend.

There will be no problem flushing with non-synthetic as long as it is of a suitable specification (i.e., not lawnmower oil). I would get the lest expensive dino I could find. Following with synthetic is fine. All motor oils are required to be compatible, if I understand correctly. Don't forget the filter.

 

[Walt T]

Re: Changing/Flushing Bad Oil

Can't hurt.

 

[Bondo]

Re: Changing/Flushing Bad Oil

A friend of mine just picked up a used boat with a 5.7 VP in it. He isn't sure when the last time the oil was changed, but he said that it looks like it has been awhile.
He wants to make sure he flushes the maximum amount of contaminants out of the engine before the winter layup. His idea is to remove the existing oil and refill it with a cheap dino oil. Run it on muffs for a while, then drain that oil. And finally, put in synthetic (which is what he plans on using here on out) before storage.

His question to me (and now to you since I wasn't sure) is it worth it to run the clean dino oil through to clean remaining contaminants in the engine? And also, if it is a bad thing to put the dino oil through the engine and then change to synthetic?

Thanks,
Greg

Ayuh,.... Other than it's really alota Overkill, I don't see any Problem,...

 

[robert graham]

Re: Changing/Flushing Bad Oil

I always add about 1/2pint of Berryman's B-12 to my oil at change time, let engine idle for 20 minutes, drain oil, replace with fresh oil/new filter....I think it may remove some sludge, help prevent stuck lifters, etc....but it always make Me feel like I've done something nice for my engine....I Did put 347,000 on a 403 Oldsmobile engine, without any issues....whatever works!....

 

[bruceb58]

Re: Changing/Flushing Bad Oil

Personally, I would just drain it and put the synthetic in and not worry about it.