Do You Change The Oil In Your Early Mustang?

Do you change the oil in your early Mustang? If so, there are a few things to consider when you do it.

You may or may not be aware that today’ s oil is formulated for new vehicles and does not have adequate protection for flat tappet cams. Until the mid 80’s most if not all vehicles produced had flat tappet cams and these engines were protected by motor oils having an additive called ZDDP (Zinc Dialkyl-Dithio-Phosphate) as a major component of the oil. This compound prevents or reduces wear between the lifters and the camshaft.

The generally accepted minimum level of protection is 1200 to 1300 ppm of zinc and muscle cars with 1600 ppm will have uncompromised protection. For race cars and new engine break-in the required levels increase to 2000 ppm and 2500 ppm respectively.

Although ZDDP is still in the oil its content has been significantly reduced because of the adverse effects it has on catalytic converters shortening their life significantly. As a result manufacturers began producing engines with roller lifters or overhead camshafts thus eliminating the need for ZDDP protection.

The American Petroleum Institute is responsible for the oil composition standards and as changes are mandated and made it issues new service designations on the oil bottles (can). Once the designation reached SM it no longer had enough ZDDP to protect our vintage cars, and the latest designation available is now SN (still not good for us).

So, what do we do??? There are several avenues and answers that will still protect our older Mustangs, but you must do at least one of them to keep from having a costly engine rebuild.

  • You could convert to a true roller motor thus eliminating the problem.
  • Some say you can switch to diesel engine oil which has enough ZDDP to protect your motor. (The composition of the oil is different than oil for gas motors and I don’t know if there are any negative effects of taking this avenue.)
  • Oils are now being produced for the vintage car enthusiast that does have sufficient quantities of ZDDP in them. They are pricey though.
  • The simplest avenue to take is to use a ZDDP additive in the oil of your choice when you change it. Numerous ZZDP products are out there and I personally use the product Cam-Shield. I’m not saying its better than any of the others, but it has served me well.

Remember to change your oil, but don’t forget to add ZDDP concentrate.

Happy trails in your Mustang.
Scott Robinson

Written by MustangAdmin