Doctor Diesel

Change for the better?

Greetings Doctor,


I have been a Diesel Car subscriber since purchasing my first Cavalier 1.7 turbodiesel new, back in 1993. I have owned an Astra 1.7 CDTi Estate since 2006 and it has been an excellent car. However, as I have now been retired (or as the French would say, become ìof a certain ageî), for 18 years, the car is just coming up to 30,000 miles, and I intend keeping the car until they take it off me, drag me out of it, or perhaps force me to have a battery job.


One thing that concerns me (and according to the internet, a large number of other Astra owners), is that, unlike the previous Cavaliers, there are no transmission gearbox oil level or drain plugs fitted, and therefore no way of checking the gearbox oil. In fact, I donít even know if there is any oil in the gearbox, except it would probably have been apparent by now, if there was not. Some owners on the internet think that the gearbox oil is filled when new, and then sealed for life. But during my working life as an engineer, in the transport industry as a Merchant Navy Certified Second Engineer, a CEGB Power Station Engineer and, for almost the last 30 years, as an Engineer Surveyor, I have on occasions experienced gearboxes that were sealed for life to prevent contamination from the atmosphere. But these gearboxes were always constant mesh, and not subject to the metallic contamination generated from gear changing etc. With the stress on the transmission from the suspension and drive shafts, it seems to me that it is asking a great deal for the gearbox oil to last the life of the car. Does the good Doctor have any opinion?


Best wishes, 

Fred Newitt


My opinion Fred, is that it would be nice if a transmission oil change was possible. But the powers that be of engineering design have seemingly decided otherwise, and made the transmissions sealed for life as you suggested. I don’t know the 1.7 CDTi engine and transmission intimately, and if you wish to pursue it you could find a local “transmission” expert and ask whether there is any way of doing the job. I somehow fear not though! You must remember though that today’s oils are so much better than in past times, that they argue that the high pressure and anti-corrosion additives are sufficient for the life of the car, and any metallic swarf (which there should not be any anyway) will not endanger the life of the gearbox. I will find a transmission expert in your area though, if you care to let me have a postcode, and you could see what they say and confirm that there is no drain plug ñ although some transmissions can have the oil changed, but it is sucked out, and filled via the level plug, until it overflows. Best regards anyway, and many thanks for being such a loyal reader over all those years.




Well now Fred… I was not really happy with my first reply, and I have been digging around for some more information. If I am correct, and your 1.7 CDTi is fitted with the M32 gearbox, then it is possible to do an oil change. In fact, it seems that quite a few owners of Vauxhalls using that gearbox have found it rather baulky and not very smooth-changing, and have either had an oil change done, or in some cases done it themselves. Some of them have used better oil than the standard Vauxhall stuff, and found a significant improvement. So there is a hexagon head drain plug, and you can do an oil change, and it is not sealed for life. I’ll have to leave it to you to take it from here ñ and you might do best going to a nearby transmission specialist as I suggested before, or a garage that knows how to do the change ñ and you could source the oil yourself, if you wanted to use something special. Some owners have used Millers 75w90 CRX NT Synthetic and found a good improvement in the change quality.


Hope this gives you some optimism. By the way, the drain plug is apparently fitted with a magnet to collect any magnetic swarf floating around in the oil.


Best regards,

Doc Diesel

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