Engine Oil - Non-Synthetic VS Synthetic

[Bill Walsh]

I have a '94 E500 with 75,000 miles and live in the Bay Area. Most of my driving is in the city and I put about 7,000 miles per year on the car and change the oil and filter every 5,000 miles. Only non-synthetic oil had been used for the first 65,000 miles and the car doesn't burn any oil. At 65,000 miles the indy shop recommended and used Mobil 1 for the oil change. I left this oil in for 10,000 miles and just had the oil changed at 75,000 miles. The indy shop used non-synthetic 10-30 oil my mistake. I called the local MB dealer to discuss the oil situation and he recommended leaving the non-synthetic oil in the car. He said they only use 20-50 non-synthetic oil on cars older than 1997 due to the possibility of oil leaks.

I know a lot of you use synthetic oil in your E500E's. What do you make of this dealer's recommendation? Thanks.

Bill

 

[gerryvz]

Largely it's just personal preference. I've never heard of this type of "pre-1997" rule applied to cars before by a dealer -- sounds to me like a rule that was arbitrarily invented by some service manager. That being said, I don't know what the breakpoint was when MB moved ALL of its cars from dino oil to synthetic as "factory fill". Perhaps someone else here on the board knows the answer to this. I do know that synthetics were first offered and used by MB in its high-performance (AMG) cars before being expanded to other "civilian" car lines.

My E500 with 65K on it, purchased in Marin County back in 2003, had up to that time used non-synthetic oil. I began using Mobil 1 at the very first oil change after that, and have used it ever since. My car now has 113,000 miles on it, and it does not leak a drop. Not a single drop, anywhere. I use a 5,000 mile change interval on my Mobil 1, and for all of my other Benzes, which use "dino" oil, I have a 2,000-2,500-mile change interval.

Absolutely no ill effects to changing over to synthetic oil. While I do believe there, in some cases, may be some limited truth to the statements you hear about synthetic oil causing "leaks" -- I also believe that for a car like the E500E that a synthetic oil is the best solution. I have not rushed to change over my 560SEC or 560SL to synthetic and have no plans to change them over. Again, personal preference.

My one caveat to all of this is that it's more important than ever to know the chemistry of the oil that goes into your car, particularly if you're using dino oil. For older cars like ours (and even older ones like my SEC) there are certain additives that the oil companies have dramatically reduced the levels of (ZDDP, for one) that can directly affect the abrasion and wear-resistance characteristics of the oils in favor of optimizing them for emissions and fuel effiiciency. I recently had to change the Chevron dino oil I was filling my cars with for the past 20 years, in favor of another Chevron dino oil that had better friction-resistance characteristics caused by the needs of the valvetrain of my M117-engined cars. So, be careful and do your homework.

Cheers,
Gerry

 

[gsxr]

Ditto what Gerry said. Make sure the viscosity is correct (xW-40 or xW-50), and change whatever oil you use at an appropriate interval... usually 5kmi for dino, or 7-10k for good synthetics (extended drains are possible but your annual usage is low enough that I doubt you're interested in this).

Be careful out there, many so-called "synthetic" oils are Group III base stocks, which is just a highly-refined dino oil that acts like a real synthetic. It is very hard to determine which oils are true synthetics these days (i.e., Group IV/V base stocks). Mobil-1 used to be one of the good ones but nowadays, only some of their viscosities are Group IV/V... I believe the 5W-40 'Turbo Diesel Truck' oil is still a Group IV/V and I use this in most of my cars (gas and diesel). The Mobil-1 15W-50 appears to be a Group III base stock now, unfortunately. Red Line oils are all Group IV/V but they are relatively expensive. Amsoil is in the same boat as Mobil-1, some of their stuff is good, others may be Group III. In the end you may not care much, as this is only important under severe service or with extended drain intervals.

BTW - welcome to the forum!

 

[S500E]

My local MB dealer also appears to have 1997 & older vs 1998 & newer "rules" for oil types. See their current service specials here: http://www.philsmart.com/coupons.aspx?t ... &s=service They are offering Pennzoil conventional for pre-1998 and Mobil 1 for 1998 and newer. Never asked and not sure why they have these suggestions.

 

[Bill Walsh]

Thanks guys for the replies and advice. I'm inclined to switch back to Mobil 1 and have it changed once a year. If the shop uses Mobil 1 in bulk how does one determine what grade it is?

Bill