I just watched this week's Motorweek. An expert from Valvoline was interviewed by Pat Goss (Goss' Garage). Their advice-be cautious of products which contain zinc; they can foul catalytic converters. I may be mistaken , but doesn't Z- Max contain zinc ? If not , then I guess you're safe. Anyway , good ole' Shelby makes a mint endorsing products. He can afford to take risks.
I'm going by the Ford owner's handbook and avoiding additives. Just my 2 cents.Everyone should do as they please.
I thought about the Z-Max engine treatment mainly because 852 sits a lot and not started for weeks at a time. Went to Advance Auto and Auto-Zone and they only sold it in a kit with engine and gas treatment of around $35. I do not want the gas treatment so I passed up on the Z-Max. If I find the engine only treatment for a good price, I may still consider it.
(BTW, in older performance engines with solid lifters, Zinc is very important but a lot of oils have had the Zinc reduced resulting in poor engine lubication in the cam/lifter area. Newer engines do not need the Zinc due to roller lifters. If you have an older engine, you may wish to reconsider your engine oil. Lots of discussions out there regarding this topic.)
I think Mr. Shelby's faith in the Z-Max product is directly related to the size of the check he gets for endorsing them. For me, I use the manufacturers recommendations for extreme service on all my vehicles. In the Bullitt's case, that would be 5000 mile oil changes. The only thing that I will be doing "above and beyond" those recommendations is to use fully synthetic oil. I have absolutely no scientific proof that synthetic is better, other than the anecdotal stuff I read but, it makes me feel better. In addition, I've used this methodology for years with some pretty high performance stuff (Motorcycles and cars) and never had an oil-related or wear issue with the internally lubricated parts of an engine. Again, anecdotal and not scientific but it has worked for me.
If you install a ESP preluber you can save a lot of wear due to engine start-ups. SAE suggests 80% of all engine wear comes from cold starts. I also believe their are some other studies out there that suggest that 90% of engine wear comes from starting a engine after it has been sitting for hours, let alone days weeks and months.
Synthetic oil is better than dino oil, especially if the engine sits for periods between startups. Syn will cling to the engine's internals much longer than conventional oils, affording more protection when starting up, especially in colder conditons. I run synthetic in the Bullitt, daily driver and M/C.
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