Here is some information that might be interesting and which I would like your opinion.

Yes yes I know, you say "another oil thread" but this time I will talk especially of catalyst vs. oil.

When I asked what is the Harley Davidson API classification, most seem to say that it is an SG, which dates from 1995, because of the amount of zinc and phosphorus it contains. If you look at the list of the best known brands, you will see that despite the fact that the SG API contains 1300ppm and 1200ppm Zinc Phosphorus, HD oils exceeds this standard with 2000ppm of zinc and 1300ppm of Phosphorus.

API SG (Obsolete): 1300ppm Zn / 1200ppm Ph
API SM & SN (Current): 800ppm Zn / 800ppm Ph

Harley SYN3 20W50: 2000ppm Zn /1300ppm Ph
BMW 15W50: 1100ppm Zn / 1000ppm Ph
Castrol 10W60: 1300ppm Zn / 1000ppm Ph
Mobil 1 15W50: 1300ppm Zn / 1200ppm Ph
Amsoil AMO 10W40: 1400ppm Zn / 1300ppm Ph
Amsoil ARO 20W50: 2000ppm Zn / 1300ppm Ph
Prolab Legend 20W50: 2000ppm Zn / 1300ppm Ph
Red Line 15W50: 1000ppm Zn / 900ppm Ph
Royal Purple 20W50: 1000ppm Zn / 3200ppm Ph
Valvoline MAX 20W50: 900ppm Zn / 700ppm Ph

In the current API standards such as SM and SN, they have significantly reduced the amount of Zinc and Phosphorus (800ppm and 800ppm) because of the catalysts and anti-pollution standards. These quantities have been reduced because the Zinc and Phosphorus is poisoning and cancel the effect of the catalyst and makes it useless. So ... Why Harley Davidson motorcycle that are equiped with catalysts since 2010, has not changed their motor oil formulas?

The V-Twin engines need Zinc and Phosphorus which are high performance anti-wear and anti-friction additives. So if I have to choose between a much current SM or SN which is less efficient and less resistant than a standard SG because of the catalyst, I prefer to remove the catalyst and keep the class of oil that will protect my engine.

 

But only to a point.

Zinc is considered aggressive meaning it tends to overwhelm other important additives including detergents and phosphorus if too much is used.

If one is going to run the oil for a very short time, higher levels of zinc are OK. But putting thousands of miles on a high-zinc oil that's meant to be used in everyday street riding may not be helpful and could actually result in accelerated wear.

 

Where did you get those numbers? They seem way too high . When Harley says to use a SG rated oil, that means to use what meets at least that spec. Harley motor oil appear to use Boron instead of high amounts of Phos and zinc. Go to BITOG site and check the virgin oil analysis for Syn III, to get the correct current numbers. Check the other oils listed to see what numbers most current oils are running. They base the amount of anti- wear additives on a 5k service interval. Whats left after 5k miles, is the true story of how much protection you've provided the motor.,,

 

The oils that use low ZDDP additives use ashless friction modifiers that will not show up on a VOA or UOA. Oil technology has come a long way in even just the last 10 years. Castrol High mileage oils always show very low ZDDP but produce the least wear numbers compared to any other oil. The test methods for uoa are out dated and look for whats in oil formulations of 20+ years ago. They need to update how they test and learn how to test for the newer ashless friction modifiers, what they are and how they work. The ashless friction modifiers also last longer. On top of that the ZDDP is not the same in every oil. Some activate at lower temps than others will. Could be good or bad depending on what kind of rider you are. Around the block flower sniffers will be better off with low temp activated, but a UOA or VOA will not be able to tell you what kind it is.

Oils with 1000-1200 ZDDP will also have the unseen ashless friction modifiers and be far superior to the older oils and tests looking for just ZDDP.

The JASO spec limits ZDDP in the MA/MA2 spec and its not much better than API SN oil has. In our non shared sump system its best to find an oil with 1200~ zddp that warns against wet clutch use. The JASO spec has an extra friction spec to it for compatibility with wet clutches, we dont need extra friction in our motors.

There is too much more to todays oils than to judge them by the ZDDP numbers. Detergents will fight against zddp and if the oil has high detergent levels then a high zddp number is inane. Detergents can also be ashless so theres no way to really know.

Best bet is to run a UOA and look for low wear numbers. Even if it only has 800 ZDDP and low wear numbers then there is a friction modifier in there that does not show up on UOA.

Ignore the rest of the UOA and look at the wear numbers. Oils like M1 that produce the highest wear numbers in UOA obviously have less ashless friction modifiers, while other oils may test out with less zddp, and have less wear. Use the oil with the least wear and dont worry about the zddp flavored koolaids.