gadfly@ihu1m.UUCP (Gadfly) (02/07/85)
--
I asked about this a few months ago, but got no replies.
Since spring is now, in theory, just around the corner,
and it's getting to be that time when (fair-weather) riders
think about pulling the beast out of the garage and reviving
it, maybe there will be more interest this time around.
Unlike cars, motorcycles use the same oil in the engine
and in the transmission. Some motorcycle oil manufacturers
claim that because of the added shearing forces on the oil
by the transmission gearing, automobile oils do not provide
sufficient protection. One letter to a cycle magazine last
year (can't remember which or when, dammit) stated that
an SAE-40 automobile oil in a bike will degrade into SAE-30
in short order. The letter came from a MC oil manufacturer,
of course, hardly a disinterested party.
I've been using an automotive oil, Valvoline 20W-50 super racing,
in my 90, 200, and 500 for years, and have had no problems. But
the engines do complain mightily when I go to start them in below-0
weather--their poor guts are swimming in molasses. 10W-40 doesn't
look much more fluid on a frosty morning, though.
Some questions, then: Should I worry about lubrication failure
at low temperature startups? If so, is such failure more likely
than from a lower viscosity oil becoming too thin at operating
temperature? So what if your SAE-40 turns into SAE-30? Is that 25%
worse, or catastrophic? Does anyone use straight-weight oils?
Has anyone had any problems with depolymerization of multi-grade
oil under hard riding? What oils do you use, and what experiences
have you had with them?
--
*** ***
JE MAINTIENDRAI ***** *****
****** ****** 07 Feb 85 [19 Pluviose An CXCIII]
ken perlow ***** *****
(312)979-7188 ** ** ** **
..ihnp4!iwsl8!ken *** ***rkd@ccice5.UUCP (R. K. Downes) (02/12/85)
I use Kendall 20-50 motorcycle-grade oil (spring,summer,fall) which is probably similar to the oil you mentioned (for high temperature applications). For cold weather, I use a (whatever brand) 10-40 weight oil. Due to the viscosity at this temperature (and the questionable design of BMW oil filters), I start and run the bike (for the first 10 miles) very softly, so that the oil filter doesn't collapse from the oil pressure. I've been told (and try to follow) to change the oil every 1000 miles in the tri-season, and every two weeks in the wintertime. -- Ray Downes Computer Consoles Inc. ccice5:rkd (CCI Central Engineering systems only)
rkd@ccice5.UUCP (R. K. Downes) (02/12/85)
BTW - A number of bikes use 80-90 weight gear oil for their separated gearbox and final drive (beemers, guzzis(?), harleys(?)). -- Ray Downes Computer Consoles Inc. ccice5:rkd (CCI Central Engineering systems only)
grego@athena.UUCP (Grego Sanguinetti) (02/14/85)
Well I use Kendal 10-40w now because it's good oil and I work very
close to a distributor. I have used Caster oil, Valvoline, .... and
they all work pretty well except at extreme temps. When it is below
freezing, and you insist on ridding (better man than I GungaDin!), no
oil is really going to do the job before the engine is warmed up. I
would suggest rigging an electric blanket or dipstick to warm the
oil up before starting the engine. Cold wheather starting is hell on
engine internals. Engine tolerances are all designed for operating
temperature. that means that parts are *MUCH* tighter when the engine
is cold. This means wear and tear in a big way.
The only time I've run single weight oils in a bike was in 4stroke
racing engines. In that environment temporatures are kept in a known
range and warm-up time is very controled. The engine oil only had to
survive for a couple of engine-hours and all in one or two days. We
used 40w since the engine was running a high temp. We had no problems
lubricating the top-end. We did, however, enlarge the oil galleries
and fittings.
The major problems with using single weigth oils in
street bikes is the conflicting requirements of the transmission and
valve train. The valve train wants thin oils so that the pump can get
enough oil up to the cams and tunnel it through the tight cam bearings
and valve mechanics without introducing mechanical resistance due to
heavy oil. The transission on the other hand, wants thick transmission
oil to stick to the big gears. Remember that the transmission turns much
slower than the valve train.
YACS (Yet Another Compromise Situation!)
Grego Sanguinetti
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