Driving my fathers '91 W126 500 SEL at the moment. It's been parked up for 2yrs and appears to need a gearbox overhaul and tune-up. Thinking of fitting 16" alloys ex my '97E with 215-55's. Any chips out there for this engine? Would a K&N airfilter and fully synthetic oil be okay? Does the 4spd auto take special oil or standard tranny fluid? Any advise on further suspension and engine mods welcome. Good budget to put her right.

In europe the 500SEL was available in 1990 & in fact only US & japan got the 560SL. Yes you can use DEXTRON trans fluid & these cars are fairly quick in stock form. A K&N filter will out-perform a dirty air filter, but frequent replacement of reqular elements will do just fine & protect engine much better.
Chip tuning on CIS fuel systems isn't very beneficial.
Lowering springs will help w/handling & so will HD shocks.

[This message has been edited by M.B.DOC (edited 08-02-2000).]

W126 500SEL and 560SEL were available side by side in right hand drive up to very late '91. The 560 didn't sell well here (Ireland) because of the price premium over a 500 (if I remember correctly equiv. US$20k at the time). Also the uprated suspension didn't work on Irish roads, 560's were notorious for bottoming out and tearing off the sump. Have booked the car in for a tranny overhaul in 3wks. Are you sure about the fluid? I seem to remember earlier 500's needing Whale Oil or something very exotic like that. This car is my fathers 10th 500 between '81 and 91. For some reason he decided to keep this one. In his career he's had over 60 Mercs, stretching back to his first, a '58 180D. I'm on my 7th, a (Euro) '97 (yes '97) E300Turbodiesel. She came with the 16" Avantgarde wheels which I've swithced to 17" AMG's. It's the 16"s with 215/55 Continentals that I want to fit to the 500. Ant thoughts on the fully synthetic oil? I've put this in my car and it was well worthwhile, but a little concerned about putting it in a motor with 115k miles up.

A good quality regualr motor oil changed regularly will be just as good for your 500 as a synthetic. With the high milleage you have to consider how much longer you will be keeping the car, factor in how many oil changes, etc. I really don't think it will add any more to the engine life if you look after it well. Those engines are designed so well that with proper service they can last much longer than the rest of the car, which is a long time.


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Jason Priest
1986 420SEL

Thanks for the advise on the synthetic oil. I'll stick to regular. Driving this car full time for the next month or so, and I'm really starting to enjoy it again. Much, much softer than my E300Turbod, but that's how my father likes it. Took the tyre pressure up from 25 to 30psi all round and much prefer the feel. It's on stock 205-65-15's. Doesn't feel anything like as quick or as urgent as my own, but I'm putting that down to the 5spd auto and a huge amount of torque from a chip job on the diesel. Also the 500 is way out of tune so the comparison is not fair at the moment. For your info, a '91 500 is only worth about US$5000 here today, so there's no question of EVER selling it.

Should be worth more....nice ride.

Keep it!