(T) Gearbox Oil Change

Just recently started using Millers Diesel Sport 4 fuel additive and am finding now that the JTD is quicker to rev up that the slow notchy gearchange lets the side down and spoils the overall effect. The car is coming up on 5.5 years & 60K old and the last 40K were racked up by me in the last 2 years

I am thinking of changing the gearbox oil to see if that improves the quality of the gearchange. Gearbox & diff share the same oil and would appear to take 2 litres. Castrol recommend Syntrax semi synthetic SAE75W/90 grade and Halfords locally have this at £12.49 / litre.

I have read on an Alfa forum that 147 owners change their gearbox oil to ATF (AutomaticTransmissionFluid) to improve gearchange quality. I am also aware that Redline & Motul make fully synthetic gearbox oils capable of handling more extreme use. I don't subject my car to extreme use, I just use it a lot.

Bearing in mind the exploding Stilo diff/gearbox horror stories on here could someone give me a clue what I should replace my standard gearbox oil with?

I don't think there's any connection between the issues with the 1.2/1.6 box and the JTD box. I gather the problem has little to do with lack of lubrication anyway (although I'm sure a few failures must occur due to the owner not checking the source of oil leaks )

I'd go for what's recommended - certainly can't do any harm

just to give you an idea of price from fiat dealer I got 2 litres of the tutela synthetic 75w for £21 they told me the recommended now is the tutela technyx gear oil,,nice and easy to do once I had figured out that it is a case of just draining the old and adding the correct amount as the jtd does not have the oil level bolt to flow from when the right amount has been added.

So you can't actually check the level then - only change it

Never realized that. Normally the filler plug is also the level plug of course.

seems that way Argo, the jtd has the filler hole on top of the gearbox where as I think the petrol versions are the old way with the filler hole on the side , I wanted to check the level on mine and searched the gearbox for the old filler holes on the side ,could not find it posted a question on the forum and was informed that there is not one on the jtd but a case of empty and fill with right amount , my old oil was still pretty clean but one of those things that you can not tell until you drain it but least for peace of mind I know it has been done now

On geaboxes fitted to Stilo Jtd 8v engines, the filler plug is also the level indicator. I think those fitted to 16v engines have a dipstick on the gear box adjacent to the diff. crown wheel housing.

I bought 2 litres of Tutela ZC 75 from Fiat last week. Price was £11.69 a litre incl. VAT so sometimes things are cheaper from the dealer. (not often though). Just bear in mind that the bottles supplied by Fiat don't have the dispenser pipe on the top so you would need to improvise something to get the oil into the gearbox.

Make sure you can get the filler plug out before removing the drain plug just in case the filler plug is siezed or gets rounded off.

Gearbox capacities are:
1.98 Ltr. for 80bhp or 1.65 Ltr. for 115bhp
I don't know capacity for 16v engine.

Dave.

obviously two typres of casings for the gearbox then my 115jtd filler plug is on top of the casing as seen on the eper, main thing is that if you can not find the filler plug on the side of the casing and you have the large allan socket filler plug on top then it is the drain and fill type I found it a lot easier to fill but a shame not able the check level thought there would be at least a small 10mm bolt to take out for the level check

Seems I may have to 'eat my words on this one' I've searched here and on the Alfa forums and the general consensus is that there is no filler/level plug on Jtd's.

I was under mine last week and there was definately a hexagon drain plug at the bottom and another one exactly the same about half way up the gearbox next to the N/S drive flange. I'll have to check that again next week. Perhaps it's just a retaining plug for something in the diff.

Dave.

A JTD has 3 plugs in the gearbox. A drain one at the bottom, one to set the correct level (at the top of the diff) and the filling one on the top of the box (take battery tray off for easy access)

Drain using the lower one, open the level setting plug and leave it open, then fill from the top one until oil starts to come out of the level one. Job done.

I used that Red Line Synthetic oil in a gearbox a while ago to try and improve it. It actually made it more notchy. I would recommend only using manufacturers specification oil in the gearbox as you can't go wrong with it.

I can recommend Mobil 1 SHC synthetic gearbox oil. Really smoothes the changes...

http://www.opieoils.co.uk/p-806-mobi...-gear-oil.aspx

will check again for the oil level plug on mine John55 be handy if there is one as I was supprised not to be able to find it then I was looking around the sides of the gearbox casings but now you have pointed me in the right direction to look at top of diff will check and see next time I am under that way as for filling it was easy to squeeze a plastic funnel between the gap of the engine and battery box and just gently add the oil without much luck of finding the filler level plug I just added 1.65 litres with ease.

Thanks to everyone who took the time to comment

Fiat Dealer has had my car today for an MOT which, after a few sidelight bullbs, it passed! Asked them to check the gear change too, judging by the additional 7 miles on trip B (reset this morning) did road test it to check, they comment that it seems normal.

If I get a break in the weather this weekend I will check to see how many filler plugs I got and if there are any signs of leakage, if I do see a level plug at the side of the NS Drive Shaft CV will check the oil level too.

With regards to the semi or fully synthetic question have seen threads on an MX5 forum that, like john55 suggests, upgraded gearbox oil that differs from OE spec can make things worse rather than better! Didn't want to go there and therefore this thread

i would replace like for like tbh.

i also thought this would be a 10yr old car + thing, only had to do an autmatic range rover (me mates) to see if it cured a bad auto change. it didnt

Been busy but just an update... decided to play it safe, per your suggestion BBS, went for the up to date recommendation of what Fiat put in to start with (75W80) in the form of Comma SX75W90 GL5 semi-synthetic which was £13 odd from a local motor factors.

Did it last Friday evening and my JTD does have 3 plugs, 1 fill / 1 level behind N/S Drive Shaft / 1 Drain. Removing engine underrtray gives access to level & drain plugs and cracked all 3 first to ensure issue free job. Found john55's suggestion of removing the battery box didn't make too much difference to fill plug access... ended up using feather dusted handle tube screwed into fill hole which meant I could pour the gearbox oil at brake fluid resevoir height down a secured tube. Car not quite level so stopped at 1.75L despite nothing coming out of level plug, checked with my little finger and oil just behind bottom of level plug hole thread. New oil is colour of sunflower oil Old oil was colour of slightly diluted cola

Difference was instantly noticeable just pulling the car back onto the drive. No de-clutching for 1st nor waiting to select reverse... just went straight in at the first attempt. No more de-clutching and/or crunch wincing 1st->2nd, 2nd->3rd & 3rd->2nd. Just slicker on the whole and very worthwhile @ £13.

Interestingly Vavoline website says check gearbox oil every 90,000 km = 55935 miles, which is approximately around the mileage when the gearchange started to deteriorate noticeably...