Need your ideas on my transmission's strange behavior

[pgrindstaff]

Last week I decided I would tackle the terrible job of replacing my transmission oil. After a good bit of research I decided that Royal Purple Synchromax was the best choice. After I finished the job I took the car out and everything was fine. Yesterday morning on my way to class shifting to second gear started becoming more difficult than usual. I am not sure if I accidentally tried to shift to second with the clutch not fully depressed or what but it feels like it is resisting the shift if I am over 2k rpm. Today I noticed that 2nd and third give me more than usual resistance but not all the time. I am almost positive I put plenty of oil in when I replaced it. My greatest fear is that I am going to have to have the transmission rebuilt or replaced. If any of you have any ideas please share them with me. I hope I have sufficiently described the problem, but this may be one of those things that you have to feel it to know what's going on.

Thanks,
Patrick

[Ross]

You don't mention if this oil change was a matter of maintenance or you are attempting to correct a problem.
Assuming the former and the trans was operating correctly before I'll speculate that one of two things are the likely cause.
The oil you used isn't compatible with your gearbox. The synchonizers rely on the drag of the oil to do their job, wrong oil-bad job.
Your clutch may not be fully disengaging, either from a hydraulic problem or the pressure plate failing.
There certainly seems to be a correlation between the different oil and the different manners of the gearbox. Not being able to drive it, hear it or feel the action of the trans it's tough to say but me thinks the oil is the culprit.
BMW spends a lot of time figuring what lubricants to use, unless the gearbox has been modified somehow I'd stick with what BM says to use.

[pgrindstaff]

Ross, I changed the oil as a matter of maintenance as I had no idea if the previous owner of the car had ever had it done. Unfortunately for me, I found that they had after I pulled the drain plug. The reason I chose RP Synchromax was due to this post. I will admit that I did not verify the validity of this person's statement but had read that people have used this oil without problems.

There certainly seems to be a correlation between the different oil and the different manners of the gearbox.

While I would like to agree with this statement It does not explain (to me) why everything was fine/normal immediately following the oil change and for the two days following the change.

I suppose if the problem does not go away on its own, which I doubt will be the case, my best bet is to let someone take a look at it and go from there.

Thanks for your help

[bsell]

While I would like to agree with this statement It does not explain (to me) why everything was fine/normal immediately following the oil change and for the two days following the change.

I suppose if the problem does not go away on its own, which I doubt will be the case, my best bet is to let someone take a look at it and go from there.

Thanks for your help

Ross' advice about a possibly coincidental clutch failure sounds right on and would explain the two-day delay.

To prove it isn't the oil, you could swap gear lubes to the BMW-specified oil and see what happens. This would be the cheapest way to prove the cause.

Brian

[pgrindstaff]

Ross' advice about a possibly coincidental clutch failure sounds right on and would explain the two-day delay.

To prove it isn't the oil, you could swap gear lubes to the BMW-specified oil and see what happens. This would be the cheapest way to prove the cause.

Brian

Cheap is such a relative term . At $138 for 5qt of the BMW oil it isn't exactly cheap but you are correct, it is the cheapest.

[Ross]

The owners book for my '94 calls for ATF, the cheapest scenario.
Can anyone confirm '95 to be the same?

[pgrindstaff]

The sticker on my transmission says ATF.

From RP website:

1983 - 1992: inspect for color-coded label typically affixed to passenger side of the transmission
BMW Green label (SHC 630) Max-Gear 75W90
BMW Red label (DEXRON III) Synchromax
BMW no label (80W GL-4) SAE 30
1993 - 1997, all models (DEXRON III) Synchromax
1998 & newer BMW Yellow label (Esso MTF-LT-1 PN 83229408942) Synchromax
1998 & newer no label (SHC 630) Max-Gear 75W90

On RealOEM it shows that there were two stickers, MTF-LT-2 and ATF. This may seem like a silly question but why would the same transmission be (in)compatible with one of two of these fluids. Shouldn't there only be one type of fluid for one model transmission?

[pingu]

The 5HP30 gearbox is the same - it is specified to use one of two diferent auto fluids, depending on the colour of the sticker.

On the 5HP30, I think the early and late models use a different oil so maybe the gearbox manufacturers used diferent parts for the later models than for the earlier models. Maybe something similar causes your gearbox to need one of two fluids?

[Ross]

The sticker on YOUR box says ATF that's all you need to know.
All the different oil refiners are going to want to sell their product so compatability is going to be liberally interpreted.
Put the ATF in and hope it ain't the clutch.