Should I Add a Zinc Oil Additive?

8 bucks for 4 oz. added to every 4-5 quarts of oil doesn't seem like a cost effective way of combating the problem of not having ZDDP in today's (non-racing) motor oil. It would be better to buy oil that already has that ingredient in it.

Here's the viewpoint of Jake Raby, a highly respected VW engine builder, on his website. See the 2nd post there.

This site has more information than a person can absorb in one sitting. There are a few FAQs specifically on ZDDP. The site also recommends three brands of oil with ZDDP in them.

-- Randall

Or simply buy a Diesel spec oil which still contains Zinc..

J.

According to this site, here is an explanation why diesel engine oils shouldn't be used in gasoline engines.

Also, what was true about the ZDDP content in diesel oil a year ago isn't true today. The current diesel oil that meets the API CJ-4 classification has reduced levels of ZDDP compared to the previous CI-4. Check out the last paragraph at:

-- Randall

I,ve been using an oil claimed to suit petrol and "light diesel engines". Trying to put aside the placebo effect I,ve noticed that starting isnt accompanied by the same noises as the usual petrol only. Definitely seems quieter. John

Since I already had almost a case of Castrol on the shelf, I went ahead and ordered 3 bottles of ZDDP (plus) today. They charged me $9.95 for ground shipping which brought the total to $34.24.

This is the way to go. The "good stuff" usually comes in 1gal or 5qt (Walmart) jugs, since this is how the big-rig guys buy the stuff. I've used Shell Rotella straight 30wt in aircooled VW and 4cyl Porsches and it works well and is cheap. The cheap part is important, because if you have a carb(s) your oil is going to be comtaminated with fuel in a relatively short time. The point is that an expensive full synthetic or "racing" oil will need changing before any cost benefit can be realized. The so-called HDEOs are such bargains that you can change them at very frequent intervals. I also have a couple of friends who track their early 911's and use either the Shell or Delo 15-40wt with great success and aren't afraid to change their oil after 2 track days (one of the cars, with trombone oil cooler, holds

14+qts!) Bill.

Yes, it was the Rotella I had in mind. Even sold under the same name up here.

J.

Does that mean that the Shell Rotella oil they sell in local stores does not have the zinc additive?

It would seem that adding the ZDDP (Plus) additive or Brad Penn oil with zinc would best the best ways to go. What about Royal Purple?

I would like to be able to buy it at a local store.

=20

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Does that mean that the Shell Rotella oil they sell in local stores is for diesel engines that make a lot of soot and reduces the ZDDP to a level not satisfactory for gasoline engines?

It would seem that adding the ZDDP (Plus) additive or even better using Brad Penn oil with zinc would best the best ways to go.

What about Royal Purple?

I would like to be able to buy it at a local store.

It means the Rotella has the desired zink content, does not soot(the diesel itself does that) and stands up to the extreme bearing load a big diesel goes through. Yes, there are non diesel spec oils on the market which works well, Royal purple has been mentioned, as have other small U.s. only companies.

Rotella has been around for a long time being made(blended) by a well known company. It is your money and your choice..

If you care to read through some of Rabys writings and less than scientific testing(he swears to hands on..), he has come up with a small U.s. blender which supposedly is great, his words not mine..

J.

I think the point is this: If you have lots of money &/or just like to know that you have the latest and greatest motor oil in your sump (& there's nothing wrong with either) then there's really no argument to be made. My point was based on value/price vs. the effective life of the motor oil. With typical carb setups, any oil you put in there will have to be changed in a relatively short time due to fuel contamination. While some of the botique oils might not shear down as quickly, they'll still have to be changed at a short OCI. Among the more reasonably priced oils, the HDEO's for big-rigs are (IMO) the best, because they have to meet the heavy demands of commercially operated diesel engines and don't have to concern themself as much with negative effects on gasoline auto cat converters. Certainly, some of the "true" synthetics like Mobil1 15-50, RP, Amsoil, Redline, etc. are great oils, but maybe not great enough to stretch out an OCI in a carbed motor when the same money can buy multiple 5-gallon jugs of good HDEO allowing numerous oil changes for the same (or less) money. JMO. Bill.