Have a 96 e36, it has about 80k on it and runs fantastic, pleasure to
drive. However, when the vehicle is stationary and idling, there will
be the normal hum of the motor then a "tock" sound. It is rather faint
and can only be heard when sitting in the car with the doors closed, I
cannot hear it when I lift the hood. I read in some places that it
could be a sticking valve, or something similar and to remedy this add
extra oil or synthetic. Well the problem is that I just bought it and
the service information is unavailable. At this point I do not know
whether its running on mineral or synthetic oil. I don't want to add
one or the other and cause any damage, as the car does have 80k on it
and may be a little more sensitive than a newer model. Any
Are you describing a noise that is tied to engine speed? If you rev the
engine a bit does it go away?
You may be thinking of the VANOS noise. It seems to happen if you use
too thin an oil. The M50 engines seem to need at least a 40 weight oil
(second numvber in multi-vis like 15W40) to build adequate oil pressure.
20W50 is fine for your car too as long as the temps are not too low.
Pick whichever oil you want to run in the car from now on and just
switch to it. Synthetics and conventional oils are always compatable
and will not cause any harm at all to have a little of one left over
from the draining.
Because of the symptoms you describe, I would suggest you try using a
15W40 oil (conventional) unless the temperature will be below freezing
regularly. In that case, I recomend running 5W40 full synthetic oil.
I do not recommend using 10W40 conventional oil (ever) as the viscosity
modifiers break down too quickly and you end up running too thin of an
oil after a few thousand miles. Convetional 10W30 is only recomended
from 0 deg.C up to a temperature of 10C (50F), so is not very useful either.
By the way, this same information can be found in the owners manual for
your car, as well as the BMW TIS if you have access to one.
Thanks for the information, I was just really concerned about the
possibility of changing to a different form of motor oil and the
possibility of adverse effect, i.e. leaks. Based on your
recommendation I will simply change the oil and use 15/40.
Also, another question. Based on the aforementioned problem and, if in
fact, the oil weight is the determining factor causing the VANOS
effect. Would a thinner weight oil also contribute to the car
requiring a greater period of time to turn over and start. For
example, in the morning the car takes a considerbly longer time to turn
over and start than in the afternoon. It seems that when the car sits
for 10 hours +, it simply does not fire up as quickly. This raises my
brow abit. Would a thinner weight motor oil prevent a quicker start
due to the combination of overnight inactivity and dropping overnight
tempatures. I am fearful that this may be a major problem, I live in
the N.E. US and the temperature drops considerably over the course of
winter. Any thoughts.
Fred W wrote:
Actually, it would be quite the opposite. That is, a thicker oil (one
with a higher first number) would likely make the engine harder to start
when dead cold. Of course the effect will be increased as the
temperature gets lower, hence my recommendation for using 5W40 sythetic
in the cold dead of winter and 15W40 conventional during warmer months.
If you do not need to change your oil seasonally, then stick with the
5W40 synthetic year round as it gives you a nice low weight oil when
cold, but also has a high viscosity when hot.
BTW, pretty much all cars take a little more cranking when stone cold.
It takes a while for the fuel pressure to rise, plus the ECU has to
increase the dwell on the injectors for the cold condition. In other
words... they all do that. ;-)
Thanks, after posting my comment I realized it rather counterintuitive
to think that a lighter weight oil would produce such results in colder
weather. I've always owned VW's and have always been acutely aware of
any change in my car, i.e. noise, smell, handling, etc. I've never
owned a BMW and am trying to get a flavor for their quirks, shoulds and
should nots. Thanks for the info, I appreciate it.
Fred W wrote:
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