Motor Oil Question (ZDDP & more...)

X2 on the Lucas HR oil.....zink PPM 2100
been using it in the 401 in the AMX and 401 in the Gremlin for some time now....order it from Summit...

will also be using it in the refreshed 360 going back in my 73 Matador after break in...






Edited by idrambler - Aug/12/2016 at 3:21pm

I have an AMC 327 in my 1961 classic Century boat. The manual says to fill crankcase with straight 30 wt. I have drained all the old oil and changed all gaskets after the engine sat indoors for 10 years. It's ready to start, but I have not refilled it yet. Should I stay with Graymarine's old recommendation, or since it is the same block and internals as a stock Rambler or Ambassador, should I follow the suggestions here and go with the multi-viscocity, zinc-added oil? The 20-50 racing oil seems too high of a viscosity for this engine. I'm in North Texas, so no brutally cold winters, but some hot summers, when the boat will be in use.

I'd run a modern 10-30 or 10-40. I don't even think they had multi back then, and if they did it wasn't as good as what we have now. It has an oil filter, right? I suspect a remote mount in the boat. If it's basically a stock engine with stock valve springs you will be fine without a zinc added oil or additive. The springs are under 300# per inch, which is about the threshold for modern no-zinc oil. Only engines with high pressure springs really need the added zinc. It's like running unleaded gas in a car not made for it. There might be a slight increase in wear, but not enough to be concerned about -- maybe 10% more. So the engine lasts 140K miles instead of 155K or so. But it's not going to hurt anything, and if the additive or more expensive oil makes you fell better, use it. Those manufacturers are counting on it!! Of course if you build an all-out race engine with a big flat-tappet cam that requires high pressure springs, you REALLY need the additive/special oil.

I would, just to be sure. I usually run around 200-300 miles on break-in, then change and run another 500-1000 miles on oil with the break-in additive just to be safe. THEN I use regular oil and run 3K or so with a carb engine, 5K with EFI (EFI runs so much cleaner tan a carb). Last time I ran break-in additive in that first full change as well... that was just a few years after ZDDP was reduced. Doesn't hurt with no cat converter, just cheap insurance/peace of mind. I don't think it's necessary though.

I run full synthetic for 10K miles in an EFI engine... sort of. I change the filter and top off at 5K, full change at 10K. At 10K the oil was pretty dark last time, so I'm going to drop back to 4K for those changes. If still darker than I'd like will drop to 3K each. At that point I may as well go back to 5K full changes though, and regular oil. While synthetic is "better" in many ways, it's not so much better than regular oil r a synth blend that it's worth it in a daily driver/near stock engine to be worth the added expense if you can't extend oil changes enough to make it at least equal out. Just my opinion, of course. A built up engine will benefit more due to the higher strain on it.


Edited by farna - Aug/18/2016 at 6:39am