Re: bmw-digest V9 #2134 - Synthetic oil in an older vehicle

[Henri Baccouche <henrib@xxxxxxxxx>]

The point I would like to debate is the synthetic oil wear issue.......

My machinist thinks that the clearances in engines which were designed for
conventional motor
oils are to big for synthetic .....The syn oil drains back too fast in these
engines.
New engines designed for Syn oils have much tighter tolerances.....

As far as the wear issue..........Conventional SH/SJ oil today changed at 2500-3000
Miles , also performs
very well. On the M20 motor this is around 300-350k miles with conventional oil.

At which point most of the oil seals will be shot no matter what oil is used......

What is your SYN oil change routine?

Henri





"John F. Korzeniowski" wrote:

> To All
>
> I worked several years in the development of synthetic oils as a chemical
> engineer.  It is my experience when synthetic oil is put into an older vehicle
> one or two things may happen.  One, any wear on the engine will be held in
> check.  I cannot say that no wear will occur but the rate of engine wear will
> drastically be reduced.  Second, if the engine has an oil leak using a synthetic
> oil will make the leak worse because the synthetic oil has a consistent
> viscosity and a greater volume of oil will flow through the leak.  If your older
> vehicle does not have an oil leak, I doubt that one will develop after synthetic
> oil is put into the crankcase.
> I personally began using Mobil 1 Synthetic in my E28 - 535i with 135,000 miles.
> At 185,000 I have not had a leak at all.
>
> Hope this helps:
> John
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