|
A good synthetic oil of the proper viscosity is usually a lot
better than conventional oil - but a lot more expensive. Thus it is best
used for applications which do not result in rapid contamination. Rear
axle vs. engine crankcase, for example.
My Chevy dealer service manager says synthetic is excellent
for rear axles used in heavy towing applications.
Re: leaking. Yes, synthetics do seem to have a way of
getting past seals etc. However, much of this is frequently due to using
too thin (low viscosity) a fluid. Since the lubricating film strength of
synthetics is so good, a lighter viscosity is often sold for an application
which was designed to contain a heavier weight oil, hence the leak.
Another case is where the synthetic cleans up the build up
around worn parts thereby causing the leak. This can also cause clogging of
hydraulic valve lifters if used in an old dirty engine. The synthetic loosens up
crud faster than the oil filter can catch it.
On the other hand, putting synthetic oil in brand new
equipment is probably not a great idea in many cases. These lubricants are
so good, that the mating parts simply don't wear and hence will not "break
in". Obviously, this would apply to devices which are manufactured to
"sloppy" tolerances and/or which require a break in period. Most modern
automobile engines are manufactured to such amazingly tight (small) tolerances
that they do not need a break in period. This was prompted by the push for
improved fuel economy, so new engines typically use lighter weight (thinner)
oils (to reduce friction) and hence must be built to finer
tolerances.
Synthetic oil is frequently used in heavy duty piston type
industrial air compressors with dramatic improvements in longevity and
performance. However, the compressor manufacturers typically recommend a
break in period with conventional (mineral) oils prior to installing the
synthetic oil. If you put synthetic in at the start, the compressor will
NEVER break in and the piston rings will not seat in the cylinder(s) !!
The synthetic oil is that good a lubricant!
Heat and automatic transmissions:
Heat is a major (if not the) factor in automatic transmission
failure. Obviously, operating a transmission in a mode in which there is a
high amount of internal slippage will generate heat and wear out critical
parts.
The most subtle problem is the deterioration of the
transmission fluid from heat. "Cooked" or oxidized transmission fluid has
poorer lubricating qualities than fresh fluid, hence it causes even more heat to
develop, thereby accelerating wear and eventual transmission failure. An
adequate transmission cooler will prevent the fluid from breaking down from heat
and the resultant death spiral. Besides periodic transmission fluid and
filter changes, per the owner's manual, you should check the fluid on the dip
stick for fluid breakdown. The two clues are brown fluid (instead of red)
and a burnt smell. In either case, CHANGE the fluid. (and consider a
cooler if you don't have one).
Maintaining the fresh quality of transmission fluid is
why a transmission oil cooler and frequent fluid changes are the two cheapest
ways to ensure longevity in an automatic (along with sensible
driving).
I do not have any experience with synthetic automatic
transmission fluids. Conceptually they should be very good, since they can
take more heat without breaking down, and have a more stable (consistent)
viscosity over a wider temperature range, and are superior lubricants (hence
less heat build up). However, they must have the proper physical
characteristics for the particular automatic transmission in which they will
be used. Therefore, I would be sure to confirm the applicability of a
particular synthetic fluid with both the fluid manufacturer and the transmission
maker.
Good luck,
Oliver Filippi
|