say NO to synthetic oil !!

[lurtch]

Hello All,

       I just coughed up $1,898.00 for newly rebuilt cylinder head from Metric Motors. While unwrapping my new treasure I found this document in among the paperwork.

    This should forever put to rest the flawed, ill-informed arguments about how switching to synthetic is a good idea for our engines!

    Regards, Larry in CA

[hank sound]

Hello All,

       I just coughed up $1,898.00 for newly rebuilt cylinder head from Metric Motors. While unwrapping my new treasure I found this document in among the paperwork.

    This should forever put to rest the flawed, ill-informed arguments about how switching to synthetic is a good idea for our engines!

    Regards, Larry in CA

Hi Larry,

May I ask what your mileage on the bottom end is, and what the weight is of your GTX oil ?

Thanks, Hank

[lurtch]

Hi Hank,

The bottom end has been completely rebuilt as well. At this point I am undecided as to viscosity. I may do the break in period on straight-up 30 weight.

[tel76]

If you read the spec: for this oil you will find that it is ideal and includes ZDDP in its formula.

[George Des]

I've used a 20w50 in my 230Sl since the day I owned it (1976) and never had any engine issues including oil burning. I recently started using a synthetic ATF in the ZF. Seems to be doing fine.

George

[mdsalemi]

Larry,

The truth is never that easy, and Mike Elias' note in your new head's paperwork is hardly a ringing condemnation of all synthetic oil products.

For our cars, and other older-engined cars, the reality of oil cannot be reduced to a "synthetic vs. conventional" with all bets falling on the conventional side.  The results have been "strongly suggested" to be the level of the ZDDP additives (which is more than one compound) which older engines need; not conventional vs. synthetic.  A conventional, modern oil for modern engines with lowered levels of ZDDP is probably just as "bad" for our cars as any oil with lower ZDDP.

It is important that each time you buy oil (probably most of us are on an annual oil change basis since we don't use the cars like daily drivers) to investigate the properties of what is out there.  I know for example, that the specifications and ZDDP content of certain Mobil1 oils is an elusive, moving target!  The oils for older engines with the proper amounts of ZDDP are not as easy to find as newer, modern oils.  You might find, for example, a dozen brands of 5W-30 oil on the shelf, and only a couple of 20W-50.

I know that in the spring, I'll change my oil again, and again, I'll start investigating what oils currently have the high-ZDDP content and are recommended for older engines and valve trains.  What I find in May of 2012 might be different that what I found in July of 2011.  I will not know until that time--the oil companies are always reformulating their products.

It is unfortunate that you needed a new head.  What precisely was the failure?  Did you or Metric deem it to be oil related?  Is this the first new head you had on your car, or a recent rebuild that needed additional work?

Some further reading: http://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_process

[Jonny B]

I will try to not get too over wrought on this topic (since I used to work for a company that makes the various oil additives).

ZDDP (zinc dialkyl dithiophasphate)(NOTE - correction, my chemistry was a bit off here, it is zinc DIALKYL dithiophosphate, not zinc DIPHENYL dithiophasphate) is a single compound, as much as any product of complex chemistry can be, that is it is a specifically manufactured chemical in a dedicated process line. It is one of many additives that are added to oil to make it "work" - think detergents, viscosity modifiers, acid neutralizers,etc. The additive package can make up to 15+% of a modern motor oil.

Motor oil additives and the oil overall is extensively tested to ensure that it does the job that the maker claims. I can appreciate what Metric Motors has stated, but I would also like to see other than anecdotal evidence that synthetics are "bad".

Yes, ZDDP is being reduced (and yes it does a great job on providing wear resistance). ZDDP has been found to poison the catalytic converters, thus the government mandated reduction in level.

There is also no question that new engines are machined to closer tolerances, and that has resulted in the much lower viscosity oils.

As to whether ZDDP makes a difference in the engines in the Pagoda is open to much debate (as we have repeatedly seen on this site). The folks I spoke with back at my former company, the folks in the engine test labs, had a number of words for the comments about ZDDP, which I won't repeat. Perhaps in a high performance engine.....

I have been using synthetic in my 250 SL since I have had it.

[mdsalemi]

Jonny,

You are NOT the only person on the forums here with oil and lubrication company experience, it would be nice to hear from others, specificially if they have any information, anecdotal or not.

What I meant when I said "more than one" regarding ZDDP is I was referring to the class of chemical additives known as Zinc dialkyl- and diaryldithiophosphates. Here's a list of about 20 of them, all with different CAS numbers:

http://apps.kemi.se/flodessok/floden/kemamne_eng/zinkdialkyl_eng.htm

Moreover, from what I've read over the years, some companies somehow get different levels of zinc, phosphorous and other essential elements in the oil by using different chemical compounds.  Unless, of course it is all bunk!

I too, have used synthetic (Mobil1) in my car since the engine rebuild in 2001.  Which Mobil1 has always been changing, as they reformulate the stuff it seems, each time I try and buy it!  I wonder if I ever used the wrong oil?  Will I ever know?

Thanks for alerting us as to why the ZDDP levels have been reduced--CAT pollution!  Some might think it is some conspiracy by the oil companies to make an inferior product!

[dseretakis]

I bought about six years worth of Valvoline 20-w50 VR1 Racing oil which is well fortified with ZDDP. It was on sale at Autozone this past winter - $2.49/quart! Lucky for me I won't have to think about which oil to buy for quite awhile now!

[Benz Dr.]

I asked Mike at Metrics about this synthetic oil warning and it's a bit different than it seems. He recomended the Castrol GTX because some people think they can run synthetic for a lot longer drain intervals than regular oil.
You can extend oil changes with syntetic if your engine is running properly. That's a big if and he thought it would be better to have everyone change their oil at regular intervals. The problem stems from engines that run rich or have diluted oil from unburned fuel. He figured it would be safer to use GTX and change it often.
 
For those who have clean burning engines I think you can safely run a synthetic with some level of extended oil changes without any real problems.

[ja17]

That makes sense Dan and I agree.  I know Frank Cozza, who ran his W113 280SL in MBCA track events for many many years, has always used synthetic oils. Synthetics oils give excellent lubrication. Changing oil often is the best and easiest way of expelling oil contaminants which accumulate during storage, cold starts etc. Storage conditions, length of storage, engine condition and usage environment are all factors to consider in oil change intervals.  Frequent changing of synthetic oil can become pricey. Using mineral oils and more frequent oil changes is often the practical alternative.

When not sure how often to change, most opt to change more frequently.

[Raymond]

Larry,

A flyer from a shop that MAY recieve co-op advertising dollars for recommending a good brand may not be enough to settle the argument once and for all.  And, for those of us who have spent many hours researching the question and reaching our own conclusions, I find your comment that our opinions are "flawed, ill-informed arguments", a bit presumptious. 

I've investigated aviation oil for older aircraft engines, I read material published by Mercedes, Shell, Mobil, and a few other sources, I even struggled to wade through an oil industry engineering article on ZDDP.  I'm still running synthetic everything in all 5 of my vehicles.