It seems that oil mfgs have been reducing the zinc and moly amounts in their motor oils for a couple years now. Well, I just crawled out of my cave and heard about it, and am worrying about the flat tappets in my vintage Bronco. Will the newer "Energy saving" oils damage cams and lifters in older engines?
What's the deal with reduced zinc and moly?
- Thread starter TheLoneRanger
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It's possible from what I hear. Might be a canidate for one of the HDEO out there. How vintage is your Bronco. Care to share some pics in the photo section?
Jury is still out. I've read great things from both sides of the argument. Supplemental additives in conjunction with reduced ZDDP seem to be better than higher levels of ZDDP alone. Do some research on here. Lot of threads on it. I just posted two in the supercharged Mustang thread.
Here is my take on it...
As with most things, there is more than one way to solve a problem. In the past ZDDP was the most economical way to give good AW protection. There were other ways (and possibly better ways) to do it, just more expensive.
As with most things, there is more than one way to solve a problem. In the past ZDDP was the most economical way to give good AW protection. There were other ways (and possibly better ways) to do it, just more expensive.
I believe so, it was a choice made for environmental reasons I hear. The focus is on making the base oil stronger so it is less dependent on additives to help protect it.
ZDDP levels are being reduced to reduce the possibility that engines using oil will "poison" their catalytic converters and the emission control system. The issue of reduced ZDDP level oil causing failure of new flat tappet cams has been discussed in Hot Rod and/or Car Craft (I forget which one, CRS syndrome strikes again!). Like Johnny above says, HDEOs like Shell Rotella are recommended to provide the required protection for flat tappet cams.
But now they are reducing zddp in HDEOs too. I think the latest is CI and that it is getting a bit low. The previous one was CF IIRC and would be sufficient.
We be up to CJ-4 now TallPaul in spec., and it is the lowest yet. Kind of gives me a warmer, fuzzier feeling that I run my boutiques...
I guess we will all have to wait and see if the newer and more complex additive structures (meaning doesn't show up in a usual OA) will keep up with the old fashioned additive packages of yore...
I guess we will all have to wait and see if the newer and more complex additive structures (meaning doesn't show up in a usual OA) will keep up with the old fashioned additive packages of yore...
I'm thinking you should go ahead and run a diesel oil in your Bronco until we all can figure out for absolute certain whether or not the PCMO oils are safe for flat tappet cams.
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IMHO, if your bronco has a used engine (your not breaking it in) with stock cam, springs and valvetrain any current spec api-sm oil in the correct visc will be more than fine. Diesel oil may even better and a good choice if your running a quick acting cam, heavy springs and questionable aftermarket cam and lifter surfaces.
Thanks all, for the replies; I feel a little better. The Bronco is a 78 with stock 351M engine. I just read about this problem on another forum, and got nervous since all three of our vehicles have flat tappets.
Castrol GTX 10w30 is what's in them now, and I have a stock of a couple cases in the garage. It's all API rated SM. Guess I'll keep the OCI's in the 3K range to make sure the oil dosen't get depleted.....?
What about mixing some diesel rated oil with the Castrol?
Castrol GTX 10w30 is what's in them now, and I have a stock of a couple cases in the garage. It's all API rated SM. Guess I'll keep the OCI's in the 3K range to make sure the oil dosen't get depleted.....?
What about mixing some diesel rated oil with the Castrol?
Run Shell Rotella T Synthetic 5W-40 in the winter and Chevron Delo 400 15w40 in the summer. Use the Castrol GTX as top-off oil or viscosity adjuster depending on how the 40weight drives.
Thanks Dad2leia. I never remember the ratings of diesel oil. Unless I can run into my oil room and look at my jug of Premium Blue, which is CI-4 BTW.
You could get a zddp additive and spike them. GM EOS has a lot of zddp (I won't say how much because I don't remember, but look in the VOA forum). Maybe 8 oz per crankcase fill to spike several hundred ppm of zddp.
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