The Zinc Files
| No matter whom in the know you talk to about our classic cars or what forum you visit the reduction of the additive Zinc in our motor oils is a flaming hot topic. In the last few years the government has required motor oil manufacturers to reduce or otherwise eliminate Zinc in or motor oils, so that Castrol GTX for example you may have swore on for many years may not be the same oil it used to be. The government through research found that Zinc reduced the overall life of the catalyst converters in our modern cars. Now in our classic cars most of them are cam in the block, solid tappet or lifter engines and Zinc helps condition the metal of the cam lobes and solid lifters and makes for longer life.
There’s tons of information on the internet about this topic and many sites that discuss this into great detail, however you need to pay close attention to the date of the information, something wrote two years ago, or even as little as six months ago could no longer apply, as to recommended zinc enriched oils, as new government regulations are changing as we speak. Al this is enough to totally confuse any classic car owner. Now don’t worry the oil companies and our governments are not going to leave us classic car owner to destroy our engines, products and additives are available for us. You going to get plenty of suggestions from your fellow classic car owners as what oil or additive they use and recommend, some knowledgeable advice, some well, not so much, oh and chances are the kid at the counter of the parts store has no idea what you are talking about. So you may ask, what’s a classic car owner to do? Oil and oil additives containing Zinc have the ZDDP label on them, and already some oil companies have recognized our concerns and are making zinc enriched oil for are older engines, so quite simply look for the ZDDP label on the oil or additive you purchase, if your oil doesn’t have it, look for a brand that does. Ok you may ask, what do you use, I’ve long been a big fan of Valvoline oils, so I in my 1967 MGB GT I useValvoline 20W50 ZR1 racing oil with does have Zinc and has the ZDDP label on the bottle, I long considered it a better product than Castrol GTX, but hey that’s just my opinion.
Ok, now I’ll talk more about my theory about zinc in motor oil. I and other engine builders feel the zinc enriched oil is a necessity for newly rebuild engines for break in of new cams and solid lifters. After break in, I don’t feel it’s needed, and I’ll tell you why, For years in our race engines we used post break in, exotic synthetic “not for sale to the public” racing oils, they were 100% zincless, and we never through engine tear down inspections saw anything on the cam lobes or lifters to lead us to believe that zinc needed to be in the oil anytime other than for new engine break in. Now you can imagine that most street classic car owners may only build their engine just one time, so follow up information is very little to non existent, so most are content to run a zinc enriched oil all the time to play it safe, which is fine, as the zinc will not hurt your motor over time. The best advice I can give you from personal experience is to break your new engine in on a crude/fossil (non synthetic) based oil that is zinc enriched or add a zinc additive to your oil for break in, remember look for the ZDDP label on your oil or additive.