1980 450SL - Qs on Oil (type) and Fluid change after sitting for a while

[supercanuck]

Morning all!

I know this is a basic question but I don't seem to be able to find a straightforward answer.

I have a 1980 450sl that I got running again last week; it had been sitting for a couple of years. It cranks up perfect and is running great, but I need to go ahead and get the oil and some of the fluids changed.

First question: What kind of oil would y'all recommend? I just called the shop and they asked me to bring my own, b/c they're telling me that the synthetic they use can cause issues with the gaskets on older cars? However, the initial research I've done says to go with like a 10W-40 or 5W-40 synthetic.

What other fluids should I get changed out as well?

Thanks!

[daantjie]

Don't use synthetic, only use conventional oils. Look for high zinc content, Castrol GTX is a good one to use. Many folks also run Diesel oil, such as DELO or ROTELLA, even in a gas engine, great oils with good detergents. As for grade, depends on where you are or how cold it is of course. 15W-40 is a good one if not too cold, or even 20W-50 if you live in hot climate. 10W-30 is a good middle of the road grade as well if cooler. Change transmission fluid too, again Castrol makes great transmission fluid, also Valvoline, but also stay away from synthetics, DEX III. Change power steering fluid (PSF) as well, Febi brand code 08972, do not use ATF for PSF. Also coolant, use Zerex G-05 Coolant, diluted 50/50 with distilled water. Brake fluid flush of course too, DOT 4 fluid, ATE brand.

[Sugar Bear]

Above is great advice. In your warmer climate I'd use a 15W-40 diesel/"C" rated oil. That motor is a flat tappet cam not a roller, look for an oil with ZDDP around 1200 ppm. Valvoline VR1 may be better if you can get it locally, if not Motorcraft 15W-40 adverts 1000ppm of ZDDP.

Good luck!!!

[Dgitmed3rd]

I’m a old school mechanic but all good advice on engine oil however on car trans that’s been sitting a while or unless you can verify the schld Mx on the trans after warming up engine & trans by driving around the block without any problems then drain about a quart or 2 of tranny fluid out & replace it with Marvels Mystery Oil, this may sound strange however but it helps with Loosening stuck valves end it softens seals without harming anything “my personally Experience I know that auto transmission with old fluid that’s that never been changed are very Temperamental & unless you got a big wallet use caution trying to completely replace all the fluid at once

[Sugar Bear]

Change the oil in the differential. Remove the fill plug before the drain plug, if you cannot get the fill plug out stop.