This is kind a spin off of Larry's post, but what gas engine for the S-Class has the best overall reputation? The 4.2 L seems to be well balanced, but not sure what others think. The 3.0 L is good, but they discontinued that. Why? Did if bode better for the E- class? The 5.6 L seems to be for speed only?

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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

mattsuzie,

I'm glad you asked this question. I'm about to trade in my 84 300SD for a 90 300SE. Since you have owned and driven both,I'd be interested in your opinion of the difference of the two.

Both cars have about 230K on them,but the SE has a brand new transmission and is generally a nicer car.

What's your opinion?

Mr. BILL

85 300D
84 300SD

Mr. Bill, I'm really impressed that the '90
300se you refer to has 230K miles !
My '89 300se has about 80K miles and I often wondered how much time before
engine problems. So far so good, except the
idle has a background irregularity.
Good Luck.

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1979 300D
133K miles
1989 300SE
1995 C280

The engines introduced in the late 1990's give much better fuel economy than earlier ones. I read an article in a car magazine a couple years ago about the guy that invented the Oldsmobile Quad 4, who did some other work for GM, was suing Mercedes-Benz for stealing his engine design. Not sure what ever happened with this, but the article said that he was suing to have all cars with the new engines to be recalled and destroyed (?!)... Supposedly MBZ officials met with this guy and basically blew him off.

Mr. Bill,

As for the exterior as you already know, the 126 body was virtually unchanged from 84 to 90. Comparing the 90 to the 84, you might get updated instruments in the dashboard, i.e., nicer speedometer, temp gauge, etc., headlamp wipers, heated seats, and airbags. (Drivers side airbags were optional in 84 – Drivers airbag was standard in 90 with the passenger side optional on the 300 – on the 420 and 560 both airbags were standard, hence more money.) Another cosmetic difference was in 84 the trim was painted grey, but in 90 the trim was painted similarly to the rest of the car (more of a modern look). My 90 SEL was a few inches longer than my SD, so there was more leg room in the back, but your SD and SE should be the same length.

As far as driving was concerned, the SEL had about 50 horsepower more than the SD. I believe the 300 SEL has 177 hp and the SD had 125 hp. Does not sound like too much, but that is a whopping 42% increase. Therefore, you’ll feel more lift from a full stop with the SEL, better for stop and go traffic. Then you get into what is your preference, diesel vs. gas. There have been some really good threads on this board about this. Larry is an awesome source of info about diesels. (Do a search for “diesel” to read these prior posts).

In a nutshell, the diesels are dirtier (but some states don’t have emission req’ts), noisier, run hotter, but get better gas mileage and traditionally last longer if the oil is change frequently. The gas engines are much more quite and have more power and acceleration (but require the changing of plugs every year or approx 17-20,000 miles). My SEL gets between 19.6 –23.5 mpg (20.5 ave), while the SD got in the high 20s all the time it seemed. So you really need to think about how you are going to drive it and maybe consider how much diesel costs in your area. In some parts of the world, diesel is dirt cheap.

In conclusion, I think it is easier to go from a diesel to gas then the other way around. I feel so spoiled on how quite it is. It is like driving a golf cart. Much easier to have a conversation on your car phone or to the person in the pass/back seat. In the end, it is all your preference. Both are enjoyable given your usage style.

Was that the answer you were looking for?


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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

mattsuzie,

Thanks for your informative responce. I think you are right,it will be easier to go from diesel to gas.

One last question. Do you really need to run PREMIUM fuel in the 300SE?

Thanks a bunch

Mr. BILL

I can answer for the 560SEL. I enjoy this engine a great deal, and from what I have read here and in other places, the 5.6l engine seems to be less susceptible to the timing chain rail failures than the 3.8 and 4.2's. The car itself is wonderful, the long wheel base and hydraulic suspension gives a great ride.
I drove a couple of 420's when I was shopping for this car, and found the increase in performance, (when your right foot gets heavy), to be more than a little noticeable in the 5.6l.
I do not see the merit in the OHC design, in any V style engine. While it allows better spacing of the valves in the cylinder head, there appears to be enough room to run this layout with a single cam.
A sleeved aluminum block is not something we are used to seeing in the US, but it is a strong design. The tech's here will attest to this, I am sure, and anyone who has worked with aluminum components knows enough to use anti seize compound and a torque wrench when assembling things. This practice eliminates most of the problems typical to an Aluminum block and heads.
I would like to drive a 5.0 l V-8. I do not see many of them around here, and I believe the lower bore/stroke ratio many let it spin up faster. I refer to the chevrolet 327 vs the 350 engines performance for this hypothesis.
This ends my rambling, for what it is worth.....

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1989 560SEL
1971 Cutlass convt. (sold)
1978 Olds Toronado (sold)
the rest are boring

Bill,

The short answer to your question is yes, you must put premium in your 300 SE, hence the "Premium Unleaded Only" marker on your fuel gauge. How much damage you will cause in time if you use lower octance fuel is unknown to me. I hope I never find out. Maybe someone violated that recommendation and can shed some light.

My understanding is that the higher octance delays combustion, thus causing higher compression while the spark plug ignites enhancing power, eliminating "knock", and decreasing causes of engine damage. This holds true for high performance sports cars and luxury cars. Premium fuels for other cars may be just a waste of money. Consult with your manual.

Continuous usage of low octance (87) fuel will eventually cause piston ring damage sooner as compared to the correct (92-94) octane fuel recommended. Remember these cars go 150 + mph on the Autobahn.

I am interested if anyone tried to bypass this and what kind of performance they got with 89 and lower octane fuels. I have not risked it and always spend the extra and get the premium.

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'89 420 SEL
'90 300 SEL
'68 Olds 88 Convertible
'84 300 SD (sold it)

I have a euro 500 and it has a few problems but it has 220+k. It is alot nicer than my friends 90 300se with a 160k inside and out sounds and fells a lot faster. just my 2cents

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Dan Younes
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1985 euro 500sel 223k
1986 420sel 86k soon 2 be
1981 300sd 285k sold
1979 240d 298k sold
1983 300sd 272k sold
1989 chrysler 2.2l Turbo
Leabaron 140k
1989 Dodge Carvan Se 295k
1994 S500
(hopefully someday)

[This message has been edited by Benzman500 (edited 09-15-2000).]