Jump to content
SAU Community

Recommended Posts

I recently changed my gearbox oil (manual) for some synthetic shell oil (75w90). the box is a lot worse to use now. i can't change into 2nd properly when cold (grinding noises) and every gear is a bit 'notchy', sometimes even when warm.

now i read in some thread that when changing from mineral oil to synthetic oil in the gearbox, sticky deposits can be formed on the gears which make the gearbox hard to use. i think this is my problem.

I was considering putting half a bottle of the engine flush stuff into the gearbox before draining it to see if that helped...is this safe to do? or is there a more conventional method of flushing the gearbox?

or am i completely wrong and something is wrong with my clutch (ie not fully disengaging)?

thanks

Greg

Link to comment
https://www.sau.com.au/forums/topic/32332-flushing-gearbox/
Share on other sites

Hey greg, maybe coz the oil grade is 75-90? its slightly thicker than the old stuff u had in there? I wouldn't put any of that engine oil flush into ur gearbox, dunno if it does any damage or not but i don't think any ones tried it before. not too sure what kinda crap is in that flush fluid.

are you changing the fluid urself? or taking it to mechanic? lol, coz i need to change mine.

I think that you should drive the car for a few more k's, and then after that change the oil again with that synthetic stuff.

Link to comment
https://www.sau.com.au/forums/topic/32332-flushing-gearbox/#findComment-648384
Share on other sites

Hey greg, maybe coz the oil grade is 75-90? its slightly thicker than the old stuff u had in there? I wouldn't put any of that engine oil flush into ur gearbox, dunno if it does any damage or not but i don't think any ones tried it before. not too sure what kinda crap is in that flush fluid.

are you changing the fluid urself? or taking it to mechanic? lol, coz i need to change mine.

I think that you should drive the car for a few more k's, and then after that change the oil again with that synthetic stuff.

hmm the owners manual say to use 75w90...but i get what your saying, an older/worn gearbox needs thicker oil. changing fluid myself. its easy to to do, GenesisR32 posted a great thread DIY thread, its in the FAQ section :D or i can show ya if you want. thanks denny :)
try using Nulon G70 instead. its great stuff! i had the VMX80 in mine but felt alot smoother with the G70 in it 3 weeks later.

if that fails, then do the flush but i wouldn't recommend it though.

yeah i put a tube of G70 in...it made a bit of difference but its still really crunchy when cold. i might try this VMX80, everyone seems to speak highly of it. if that doesn't work then its redline time. if that fails then gearbox rebuild time lol :D thanks mate :D
Link to comment
https://www.sau.com.au/forums/topic/32332-flushing-gearbox/#findComment-649232
Share on other sites

Vmx80 + G70 = :D

redline oil = :D:thumbsup::D but expensive

the VMX80 takes a while to run in when you put it in the gearbox and i noticed that its highly effective only warmed up properly but like you, i did experienced some crunching when cold. when i added the G70, it became a whole lot smoother regardless of hot AND cold.

dun you feel your arms muscles tightening up everytime you do the filler and drain plug?? :)

i used the redline stuff in my diff instead. :)

Link to comment
https://www.sau.com.au/forums/topic/32332-flushing-gearbox/#findComment-649343
Share on other sites

Sorry GenesisR32, I disagree. Nulon G70 is the biggest load of crap I have ever put in my gearbox. The shit is TOO slippery. My synchros started behaving in ways that resembled a slipping clutch.

I too had Shell Synthetic 75w90, which I feel comes along side the Nulon additive as being the crapiest gearbox oil on the market. As soon as I changed the oil to Shell, the shift from 1st to 2nd was hell worse. I then added the Nulon additive, the shift was still crappy and I started having synchro problems. I drained the crap (Which now looked like cows milk thanks to the Nulon additive) and replaced it with VMX80, bled the clutch...Perfecto! (well nearly) The 1st to 2nd change is significantly smoother, even in the cold. Oh and so far, no more synchro problems...touch wood! The stupid thing is that the money that I have spent so far in this little episode, I could have used RedLine Shockproof for the same money...oh well...you live and learn.

Link to comment
https://www.sau.com.au/forums/topic/32332-flushing-gearbox/#findComment-655395
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • For once a good news  It needed to be adjusted by that one nut and it is ok  At least something was easy But thank you very much for help. But a small issue is now(gearbox) that when the car is stationary you can hear "clinking" from gearbox so some of the bearing is 100% not that happy... It goes away once you push clutch so it is 100% gearbox. Just if you know...what that bearing could be? It sounding like "spun bearing" but it is louder.
    • Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
×
×
  • Create New...