Just curious, does anyone use any additives for oil, transmission, fuel, etc and what has your expericene been?

I have a minor power steering leak in my w108 and was considering using the Lucas PS Leak Stop additive, but wondered if it will do more harm than good.

I have not. Personally I'd rather deal with the cause given my 4.5's 43 years old and in excellent condition.

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1973 280SEL 4.5
2021 E450S4 AT/Wagon

The only time I've seen those leak additives work at all was on a gasket that was seeping, not really leaking. I believe they make the gaskets swell and stop the seeping. Radiator stop leaks work several different ways, I have used them to some success but always temporary. Ultimately the "real" fix had to be done. As far as gas and oil additives: I have added ZDDP to improve oil performance in a hi perf VW diesel TDI I had. I have used "diesel Purge" from Lubri Moly, to clean the injectors on my old benz diesels. I used a clear container for the supply and return lines, it was obvious it was washing something out of the injector system as I could see it coming from the return line. Whether it made a significant performance improvement it was difficult to tell. Overall I think there is a place for some of the better additives but many of the cheap ones are of little if any value. Just my $.02

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Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K

I've been in and around the automotive repair business for 40 years. In modern times engine oil additives don't do much though a Zinc additive could be beneficial for an older flat tappet camshaft.

On an older car, good regular oil that is changed often ( due to poor fuel control ) would be fine. I wouldn't run synthetic in an older car because the oil will become contaminated long before it wears out making things $$ in the long run. I look after a 99 Blazer and run synthetic to 8,500 - 9,000 miles before a change because the engine has good fuel control.

Stop leak additives ( and some trans fix in a can ) more or less contain traditional brake fluid to soften and swell seals, give a bottle a sniff sometime. The problem is that it can continue to swell seals turning them into mush or the seals are so hard nothing happens and the stop leak goes after parts that are already soft making them softer.

If I didn't care about the car much I might try is but from changing many rock hard shaft seals / o rings, I don't have high hopes.

Brake fluid will swell rubber that is resistant to oil , oil will swell rubber that is resistant to brake fluid. For a woods buggy I used a bit of ATF in the brake system to cure a failing master cylinder, the trick is not to use too much as the seals can swell too much causing things to jam. And don't try this on a road going car.

On a gasoline car, many fuel system cleaners don't seem to do much. The only one I use is Techron ( made by Chevron ), I've used one bottle, ran 4,000 miles then ran a 2nd bottle and that's about it. On a 99 Ford 3.0 V6 with 175 K miles, the first bottle made a slight improvement, the 2nd bottle made a noticeable improvement at light / mid throttle tip in.

For a diesel, I've used a fuel system cleaning additive ( power service ? ) on a couple of diesel powered air compressors that were sitting for may years. Other than a snappy name, I have no way of telling if it helped or not.

Never added anything to oil or ATF on my 85 and 72 model cars. Sometimes add injector cleaner to gas.

For PS, I have used PS fluids that claim to have additives that reduce leakage. Never had to rebuild PS on either car (160k and 265k miles)

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Graham
85 300D,72 350SL, 98 E320, Outback 2.5

The lucas PS additive is actually pretty good. It helps stop brand new Jaguar PS racks from leaking.

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With best regards

Al

No additives to MB, but I have in the past (before retirement & racking up lots 'o' miles on cars), I added (clean) atf at fuel filter changes to my 6.2l deez Blazer

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"I applaud your elaborate system of denial"