Regular Oil or Synthetic? Which should I use

I have a 1985 500SEL with 81,500 miles on it. The car has always had regular oil ran in it, but I thought of switching to Mobil 1 synthetic. What is your
suggestions. And, the owners manual states 87 octane gas, should I follow it, or go with 92 octane?
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I think if you try 92 you will notice a difference (I did with my 380, and I made sure it wasn't placebo by having someone else fill it up). If you don't have any leaks with regular oil, go to synthetic. If you still don't have any leaks HOORAY! With my 380, I had a small leak with regular oil, went to synthetic, had a better running engine but made a total mess of my driveway so I had no choice but to switch back (even blend made a mess of my driveway). Richard

regular
your
it,
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your wasting your time and extra money with synthetics on a car that old with those miles.... you will gain nothing other than spending more on oil... higher octane fuel is fine...
Brett.. 03, 211 E55

regular
your
it,
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Wouldn't you want to give an older car an oil that makes life easier for it? Richard
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follow
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Sahara.
price.
How about if you drive hard/fast? How about if you are running an older engine which doesn't run as smoothly as it used to? If you know how to tell good oil from bad oil,you would know that synthetic stays good longer. And if you ever tried it in an old car you would notice your engine runs smoother. Ever tried synthetic ATF in an old tranny that doesnt work right (even if the old fluid was good)? You would notice that afterwards the tranny works right. Also, cool a bottle of regular and a bottle of synthetic to about 40F, now poor them out...which one is better? On a cold start in winter your engine will thank you. Richard
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On a cold start in

Will it email him or leave a voicemail? LOL.
Huw
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I completely disagree with Brett. Higher octane fuel in an engine that doesn't need or use it is a total waste. Superior oil that keeps an engine cleaner and running longer is never a waste.
That said, I am assuming the engine is currently in good shape and has been maintained according to the schedule. If it's running poorly or has problems, then Mobil one is no panacea.
Marty
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Actually, on older engines with carbon deposits, higher octane fuel is a good idea. Plus, it allows you to advance your timing a few degrees to get some more power.
said:

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On 2005-05-24 13:50:56 -0700, "marlin"

You should never advance your timing beyond the factory spec. in my opinion. This is likely to cause excessive heat, regardless of the fuel used.
Marty
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