Is ZDDP good for your motor?
 

Many of us have heard about adding this product in order to help lubricate the flat tappets on our older vehicles. I friend of mine brought me this information about some testing done and how the lubrication properties changed when adding this product. Interesting results, also the lubricating properties of many brands of oil are tested.

http://www.nastyz28.com/forum/showthread.php?t=256590

Re: Is ZDDP good for your motor?
 

Zinc was put in oil for a reason and taken out due to full roller cams. Don't need it with all that drag taken away. Never hurts to add a little. Lucas oil stabilizer is the stuff I use...don't know if it has zinc, but man...talk about something that keeps the oil where it should be. :thumbsup:

Re: Is ZDDP good for your motor?
 

This is the story: Zinc dithiophosphate (ZDDP or 'zinc') has been used in motor oil for many years. It protects against 'scuffing' wear, like the wear between a camshaft and flat-tappet lifter. ZDDP has been slowly phased out over the years because it was found to degrade catalytic converters over time, particularly in engines that consume a lot of oil. Since the EPA mandated long warranties for emission control components, automakers switched over to roller lifters and cam follows and pressured the oil companies to reduce ZDDP in motor oil. These days, it's pretty much gone from most motor oils. Exceptions are racing oils and oils for diesel engines.

The question now is are oils containing ZDDP necessary for older engines? The answer is yes and no. It seems that flat-tappet engines really don't need much if any ZDDP as long as they are well broken-in. However, scuff protection is very necessary in a flat-tappet engine with a new cam and lifters. Without adequate scuff protection, a new cam and lifters can wear rapidly and not properly 'break-in'.

What this all means to us is ZDDP is a good thing to have in the oil you use in your GMC V-6. I think is always better to play it safe with older engines, so I use Valvoline Racing 10W-30, which contains ZDDP, in my 351. My engine is well broken in, but why take a chance? V-6 cams are not so easy to find anymore. One thing to keep in mind, however: Diesel motor oil has been used a lot in flat tappet gasoline engines, but be advised! New diesels have catalytic converters, and the oil companies are stating to reduce the amount of ZDDP in diesel motor oils. I think a racing type oil is the way to go now.

As far as additives are considered, who knows? I have never used any.

Re: Is ZDDP good for your motor?
 

I agree with Bob -- why take a chance by using an oil with minimal ZDDP? I've always used the particular Amsoil products which have high ZDDP. See https://www.amsoil.com/newsstand/cla...ar-protection/ for another explanation of why ZDDP is good for older engines with flat tappet cams. My one ton Suburban has had nothing but Amsoil's original AMO product in it since 1973. The newer Amsoil Z-Rod oils should be good too.

Regarding additives, my opinion is that they should generally be avoided. They can upset the chemistry carefully designed into an oil by the oil companies. Evidence is out there to back this up.

Re: Is ZDDP good for your motor?
 

Don't want to hog the thread, but while we are on the subject of oils....What is everyone's view or experience with Lucas Oil Stabilizer? Used it in my 305 v6 with straight 40 and that stuff was like butter for the bearings. When I took my 305 apart for a light rebuild the lucas made the oil "stick" to the bearings, and turning the engine over you could heard the oil smear around the bearings. lol Used lucas as bearing butter for the new ones. Worked like a charm.

Re: Is ZDDP good for your motor?
 

It's been a little while since I've posted here, but I have been following the threads, especially this one. I located a link which I will share with the group, and it concerns Amsoil and the use of ZDDP in engine oils. I found it to be an interesting read, and had lots of useful information, especially on engines using flat tappet cams like the Big Block GMC V-6's. I do hope you will follow the link, since the info contained in the article should answer many of your questions involving the use of ZDDP in engines, especially older, and high performance engines.

The Debate Over Reduced ZDDP and Wear Protection - Amsoil https://www.amsoil.com/newsstand/classic-and-vintage/...

Re: Is ZDDP good for your motor?
 

Thanks for the link George, some great reading there. Amsoil makes some great products, but I will say....$70 for 6 quarts is spendy. haha But worth it if it saves a $1000+ rebuild!

Re: Is ZDDP good for your motor?
 

Greetings TJ!!

Yeah, $70.00 for 6 quarts of oil is a bit spendy!! I get my Amsoil from our local Mill's Fleet Farm Store for $37.95 for 5 quarts, tax not included. I am a firm believer in Amsoil Synthetic oil not only for the wear protection it provides, but also because it flows more freely in sub-zero temperatures than crude base engine oils, thereby all but entirely eliminating "oil starvation" of critical moving engine parts in cold weather starts. To me, it more than pays for itself for the engine protection it offers.