Changing oil grades
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Elder User
Joined: Jul 2004
Posts: 637
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From: Media, PA
Changing oil grades
I've never heard of such a thing, but a friend asked me to post a question for him. Can an engine become "used to" a particular grade of motor oil, such as 10W-30? And, if after using the same 10W-30 for years, you switch from that 10W-30 to a lighter-weight oil, such as 5W-20, will the engine react, possibly with lifter ticking or valvetrain noise? I know the tollerances are very tight on the 5.4's. He had his truck in the dealer for some repairs, and while there, they changed the oil for him, using 5W-20. Now, he has a ticking noise from the engine. Just curious...
Thread Starter
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Elder User
Joined: Jul 2004
Posts: 637
Likes: 4
From: Media, PA
I think I just answered my own question with a post I read below - "Tapping noise". I'll tell my friend to change the oil out to the 10W-30 he was using and see if that changes things.
Senior User
Joined: Jan 2003
Posts: 229
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From: North Carolina
I think it is entirely impossible that an engine can get "used to" a certain weight oil. Take, for example, an engine with 100,000 miles on it that has always ran 10w30 oil. This engine (bearings, piston rings and valve train in particular) have worn together in a manner largely determined/influenced by this particular weight of oil. After 100,000 miles, it stands to reason that switching to a thinner oil would cause the aforementioned parts to not be lubricated in a manner that they have been for the previous 100,000 miles because 1) the buffer effect of the heavier weight oil is no longer there and 2) the new, lighter engine oil is now tyring to lubricate an engine whose clearances (which have naturally, increased over the years due to wear) are too much for it to lubricate as efficiently as a heavier weight oil. This is why if anything, vehicles will start at a particular weight and over the year/miles go to a heavier weight oil. His engine has not likely been damaged. Tell him to change back to 10w30 and he should be fine.
Last edited by Indybroncoman; Dec 26, 2004 at 07:27 PM.
