I asked this question before and got different opinions. On our engines (I have an 85 2.8L and an 85 2.5L) is it necessary to add a zinc supplement to the oil? Some people say no it isn't necessary for a stock motor, others say yes the engines need it. Is there a hard and fast rule on this or is it just a matter of personal preference? Thanks
I don't think you'll get a perfect answer because its hard to tell.
A stock motor running oil without extra zinc won't implode on itself. It may suffer slowly deteriorating performance due to the cam lobes wearing down. But then again, losing performance may be because of a lot of other factors.
I would also be interested in some hard data showing that zinc is necessary or not.
waste of time using any oil with high ppm zinc that has high detergent.. might as will use any oil.. as the detergent cleans the zinc off the parts,
many say for a stock engine you don't need the zinc, but I'll ask you, were you going to get a new cam when a lobe goes south, and engine rebuilds are costly..
you need low detergent oil with 1200ppm zinc.. or low detergent oil and the zinc additive,
many get away with todays oil because the valve springs are junk after all this time, even if it has low miles.. the valve springs have weakened, from heat cycles and sitting with valves open(spring compressed)
I don't have any oil leaks at all on either the duke or the V6 but I have heard that Mobil 1 used in a high mileage engine that's always had dino oil in it causes oil leaks. I just don't want to cause a problem. I agree that Mobil 1 is a very good oil.
Most of this issue is for cam lifetime... Many says flat tappet cam setup get more protection from added "zinc," full name is Zinc DialkylDithiophosphates (ZDDP). Roller cams doesn't care much. Note that too much ZDDP or burning oil can poison the catalyst because of phosphorus content.
84-86 Dukes can have Roller cam setup. All DIS Duke are roller setup.
Problem is so many Dukes were replaced under warranty/recall work, DIY to replace dead engine, etc.
84 Indy I think had roller cam setup from factory. Base model had flat tappet. 85 maybe. I've seen doc say yes, others say no. 86 all were stock.
I've never heard of such a claim but im sure the person that stated that had problems before they ever switched oils. I've been running Mobil1 in my 86 GT 4 speed for the last 20,000 miles and I haven't had any issues (at least regarding the engine.)
Zinc is added to oil for cushioning, Mainly for extremely high compression, high horsepower engines. Zinc is also activated by heat. It needs heat to actually form what is called a phosphate glass coating, if you have a stock valve train you DO NOT need a high zinc motor oil. This phosphate glass coating ONLY happens under high load/heat applications, Example; A true DRAG engine, one with little or NO cooling system. Your engine will NEVER get hot enough to utilize the zinc, other parts will fail before zinc is activated. Zinc originated from monster nitro engines, trying to find a better oil for the extreme 4 seconds of over 1000 horsepower and multiple thousands of RPM's. Most "wear" typically happens in the valve train. And the Zinc would activate phosphate glass, and fill in the valleys and smooth out the microscopic highs between metal services ONLY under extreme horsepower/heat applications. Your engine will NOT produce this.
I have been a master service tech for 30+ yrs. though I DO NOT KNOW EVERTHING. if you want the perfect oil for your engine, go with and API SN or higher oil. as a matter of fact a TRUE synthetic MOBIL1/or/ AMSOIL is the best you will EVER get. and ALWAYS use the recommended weight (5w-30) . weight of oil translates to molecule size, and bearing clearance is set for 30 weight molecules as the largest to "fit" between your metal/bearing services
And on another note, IF, your engines consume a fair amount of oil, then synthetic may not be the way to go, unless you have money to burn..........literally. Synthetics are truly the best oils for stock and moderately high performance engines. BUT, if oil consumption is already occurring then the "damage/wear" has already taken place. And you will get just as good performance from a good quality mineral based oil (valvoline,pennzoil) and you won't be throwing money through your valve guides and rings. All oils have some zinc in them, but high zinc oils are for real fire breathing monsters................so to speak.