Fuel Additives

[71Beige280SL]

I was watching a car restoration show last night. They were restoring a 1970s Triumph. They performed a compression test and found that there was a problem. As they were taking the engine apart to replace the rings, valve springs,etc. they were explaining that these cars were designed to run on leaded fuel...running unleaded gas in a car of that era causes undo wear unless a lead additive is used. This caused me to think. I have been using 93 octane unleaded gas in my 71 280SL since I bought in May of 2011. Should I be using a lead additive??

[Jkalplus1]

From my own research in this forum, it seems the generally accepted answer is "no" to the lead substitute.  However, the motor oils of today have less zinc contents than same grade oils when our cars were made, so it seems the recommended thing to do is to put zind additive (ZPPD) to your engine oil to prevent excessive cam wear.

I am doing this with my car, since it is cheap and is recommended by Benz Dr who has been working on our cars for a long time.  10W40 synthetic with zinc additive, and I run on 91 (or 94 when I can get it) fuel.

[Iconic]

I agree: No lead additive is needed on these cars (at least from one I have read).
I disagree: I don't agree with the idea of adding zinc additives or other things to your oil. I have read you don't know how they will mix or settle. You are better off using an oil where the manufacturer is responsible for insuring the additive is appropriate and usefull.
Brad Penn (mostly dino oil with a little syntetic) makes a high quality oil with high levels of zinc and phosphorus (this is what I use).
And Royal Purple HPS (fully synthetic) makes a very high quality oil with Zinc, Phosphorus, and some other secret incredient (I use this in a turbo charged car I have).

There is much written on these topics. You will need to make your own decision.

[71Beige280SL]

Thanks for the responses. Does Mercedes make an oil with the right zinc/phosphorus mix?

[Benz Dr.]

Thanks for the responses. Does Mercedes make an oil with the right zinc/phosphorus mix?

I can't say for sure but they like to sell new cars so I'm thinking, probably not.



  The only way to know for sure is to do an oil test in a lab. 1500 PPM is considered enough for most older engines. During break in, you can go twice that amount. I've asked both my bulk supplier of farm fuel and lubes as well as my automotive suppplier for the level of zinc addtives in their oil and niether have given me an answer. I assume no one ever asked before and they didn't bother to find out. Rather than wonder, I bought some additive to be sure. I will do an oil test and find out what they actually have because you can't tell by looking at it.

I'm fully aware of Royal Purple, Joe Gibs, and others, but not everyone wants to pay $10.00 + dollars per liter for oil so I use an additive recomended by my machinist. Since I'm only buying the additive and not the oil with the additive so it's considerably less at maybe $1.50 per liter of oil.