Ken,

Thanks for your input! Your comments make me want to more attribute my leaks to the fact that my wagon likely sat still 5 months/year here in New England.

And I personally run synthetic for the added protection, and do indeed moderately lengthen my intervals (change every 7,500 mi. both cars).

------------------
All the best, Michael
500E
300TE

Adam,

2,000 miles is way too soon for an oil change. It can cause stuff to go wrong. Let it go much longer than that. I always recommend 5k on dino and 7.5k on synthetic.

I run 100% synthetic(Redline oil) in my motorcycle, a 1992 Honda CBR600F2 with 56,000 miles. Went to synthetic after 5,000 miles. Motorcycles are much harder on oil as the engine oil is shared with the transmission. My bike redlines at 14,000 rpm, peak power is at 10,000 rpm, and I take it to redline almost everytime I accelerate - 0-60mph in 3.4 seconds. This bike is able to keep up with liter-class bikes only by shifting frequently to keep engine running in power band (8K-11K rpm). Warranty recommended changing oil every 8,000 miles, I changed it every 4,000 until it had 48,000 miles on it. Now, I'm going to change it every 8,000, let's see how it holds up. I know a guy who has 2 motorcycles (sportbikes), both with over 100K miles. He runs Mobil 1 only and changes oil, GET THIS, every 12,500 miles. He rides hard and his bikes run very well.

------------------
Dave

johngray,

The economy in oil changing is not related to the cost of the oil versus the mileage until the next oil change. The economy comes from extended engine life.

Even Mobil One is much cheaper than engines or cars.

The only way to clean the inside of the engine is to drain the oil. The same amount of contaminants are produced by a given engine regardless of the oil used.

Good luck,
Change oil hot and change oil often,

------------------
Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

To DSinger,

Whay do you say changing oil too frequently can cause damage to an engine?



------------------
Jason Priest
1986 420SEL

The only way frequent oil changes can damage to an engine is if you leave the filter off, the drain plug out or forget to put oil back in. That will definitely cause damage. Otherwise, if you changed the oil once a week it will NOT cause damage to an engine.

Like 420SEL, I'm awaiting the explanation of how damage is caused by excessive oil changing.

Good luck,
Change oil hot and change oil often,

------------------
Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

In my mechanic days we used a standard of 100 hours between oil changes. These were 3, 4, 6, 8 and 16 cylinder diesels, which if they weren't at idle they were at full throttle. During some operations and on several applications, that meant changing oil every 4-5 days. That was 4 gallons or so on the small engines and almost 10 gallons on the big ones. These all used dino oil.

On the radial, multi stage compressor (which was coupled to a 4-53 Detroit) we used synthetic due to the higher heat generated by the air compression, and it was changed at 100 hour intervals as well.

I only recall one oil related failure, and that was caused by a cracked oil line, which sprayed oil all over the engine room. I have seen engines toasted due to no service/oil changes, but have never seen one damaged by excessive oil changes.

I did just think of one possible scenario - constant oil changes wearing out the drain plug, not replacing when worn and the plug falling out, leaving a trail of nice new oil down the highway.

------------------
Mike Tangas
73 280 SEL 4.5

[This message has been edited by MikeTangas (edited 10-31-2000).]

Mike,

Don't forget about the excessive wear on the hood hinges.



------------------
Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

Every 2K is overkill except under unusually adverse conditions: very very dusty, many many short trips in cold weather with lots of idling, racing, or operations where the oil is severely overheated. Even the people who sell oil and do oil changes only recommend every 3K. The Click and Clack Brothers, who are actually much better mechanics than they are comedians, recommend every 5K. Every 4K to 5K with mineral oil is fine for average, everyday service.

I think there is a big misconception about what consititues normal service for an engine and what consitutes severe service. Most people think that the only things that constitute severe service are towing a load of logs up hill and driving off road in Arizona. Normal service is where the engine is given proper time to warm up and then is driven at constant rmp for an extended period of time, such as highway driving. Anythings else should be considered severe service. How many times have you come home and parked the car in the driveway, had supper and watched TV, then gone back out and driven the car into the garage? How many times has your wife (not to imply anything against anyone's wife, but I know my wife drives like this) taken the car shopping and goes to one store that is a five minute walk away from your house, parks, shops for an hour, then drive two blocks down the road to the next store, etc. This is the kind of driving that realistically happens to cars in North America. Tons of start ups, short trips, etc. And it is evern worse in winter. I don't think that an oil change every 2000 miles is over kill. Give me ten more years and I will prove it in my car. Here's a question to ask yourself too. IF there were tow identical used cars side by side, same mileage, color, condition, price, etc, and you were going to buy one of them, would you rather the car that had oil changes every 2000 miles, or the one that had oil changes every 5000 miles?



------------------
Jason Priest
1986 420SEL

Excellent posts by all. With all due respect, very little science though.

Who is getting oil analysis done on their used motor oil? I have. Results (5K between oil changes at the time, Mobil 15W50, converted at 60K) were excellent - no indication of wear, or abnormal particulates (was curious about K&N filter, I've since removed it anyway). This is my wife's primary car; can't get much more severe service than that!

A comparison of dino vs. synth vs. intervals, using oil analysis, would really help with this discussion and perhaps end it once and for all.

Ever wonder why the oil companies haven't done this (or released the results): "Based on our testing results, we find longer drain intervals to offer owners no substantial decrease in the performance or longevity of their automobile engines. Please, buy less of our oil by extending your drain intervals". Yeah right.

Brian
89 300TE 165K
84 733i 135K
Mobil 1 for both, twice per year
(well, they both use a little oil, so there is *some* fresh oil added between changes)

quote:

---

Originally posted by taaboo:
Excellent posts by all. With all due respect, very little science though.

<recommends oil analysis comparisons>

Ever wonder why the oil companies haven't done this (or released the results): "Based on our testing results, we find longer drain intervals to offer owners no substantial decrease in the performance or longevity of their automobile engines. Please, buy less of our oil by extending your drain intervals". Yeah right.

---

I believe that AMSOIL does in fact make
this recommendation. And no, I'm not one
of their pushy independent reps! In fact,
I don't use nor have ever used AMSOIL.

Used to use Castrol synth. They have lately
reformulated so that it's no longer a pure
synth and is now a very well processed
hydrocracked mineral oil. Moved to Mobil 1
instead despite the higher cost. Have run
oil analysis using 7.5K drain intervals
and am happy with the results.

I would bet that the greedy Exxon mgmt
will be shortly reformulating Mobil 1 into
a less capable product now that the two
companies are merged. When/if that happens
I'll move on to something else.

BTW I know two pro lubrication engineers.
They both run synth exclusively. One does
extended drain, one does not.

My belief is that much of the extended
drain capability is due to reduced blowby
of soot and contaminants. Synth has much
higher film strength at the ring to cyl wall
interface, so less crud is blown by into
the oil. Of course, if your rings are shot,
this won't be applicable.

In my experience: yes, synth will leak in
an older engine. Dino oil bakes to a varnish
on the inside surfaces including gasket
mating surfaces. The gasket dries out behind
this false seal. Adding synth can cause the
varnish to be dissolved away over time, and
the dried-out gasket then can't do the job.
Presto, you get a leak.

Switch to synth early on, preferably before
50K. If the engine has had faithful dino oil
regularly with good quality, it would likely
be OK up to 100K. Anything overheated or
undermaintained, don't switch. Use dino on
a short schedule until it dies.

Ron H

--

Sorry to be anally retentive, but my oil analysis consists of 3,000 mile interval, drain overnight while hot, change the filter every time, then see the engine go 380,000 miles.

Oil is cheap.

Great thread,
Change oil hot and change oil often,

------------------
Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

I'm with Larry on this one.



------------------
Jason Priest
1986 420SEL

Ron H.,

Tahnks for the synthetic leak explanation. I've seen lot's of posts claiming that leaks will occur in an elderly engine when changing to synthetic, but I've never seen a plausible explanation.

Thanks and have a great day,


------------------
Larry Bible
'01 C Class, Six Speed
'84 Euro 240D, manual, 533K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles