Oil additives

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Gregory S

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Who among us adds ZDDP to their oil when changing oil? My mechanic yesterday informed me that current oils do not contain enough Zinc for flat tappet engines. He said Rotella -T contains the most, but still not enough and he recommends adding to each oil change.
 
I just googled this, seems like your mechanic is spot on.
 
Charlie has been mentioning/advising that for many years. Only applies to older flat-tappet engines though.
 
My engines (1994) are flat tap pet engines as mentioned above.
 
Does anyone know, if and when (year) marine engines started using roller tappet. I would guess never or at least till 2009 or so.
 
Greg,
You should use Shell Rotella, I have an oil guy that has told me for years, it is the best. Also, Walmart sells it and is cheap. I Use the same in my diesel motors.
 
Our 1996 Chevy Small Block was Roller Cam. I wonder if they got into car/truck engines before the marine versions.
 
My mechanic said the same thing--- use Shell Rotella T. It has the most ZDDP of any available oil. I thought I was doing the best I could with Mercruiser 25-40. Apparently not.
 
Some Mercruiser engines were roller-cam as of 1996 - mostly the higher output versions of the standard engines. Not sure when they switched to all roller-cam though.

Thanks for posting this, Gregory! I didn't know about the zinc issue. My old 4.3 Merc was a flat-tappet engine, and I ran Castrol GTX 10-W-40 for it's entire life. Guess I was just lucky.

Going to advise my son to pick up some Shell Rotella T ASAP! (His 454 is also a flat-tappet engine, and we just rebuilt the damned thing... Don't need any more problems!)

Adam
 
You're welcome Adam. I added ZDDP to my oil as The oil changes are fresh. I will be switching to Rotella T at the next oil change.
 
Just to clarify, you're talking about the Shell Rotella T6 diesel engine oil, right? (It's actually advertised as "mixed-fleet oil", meaning it's OK for gas or diesel engines.)

Want to be sure I get the right oil!

Adam
 
I always add a bottle of STP oil treatment at each oil change. It has all the stuff that modern oils lack.
 
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