Date: Thu, 17 Dec 1998 15:44:56 GMT From: Ladislav Bashtarz <ladislavnopsamat.com> Subject: Re: question: transmission fluid....Help me, no manual.
Ken Washington wrote: > I hate to burst your bubble, but your experience does not necessarily > prove anything other than being too lazy to change the oil in your 5 > spd. The owners manuals for the 87 900 and 87 9000 both say check and > top off every 30,000 miles...Any person with common sense, who works > around cars should know and understand that the lubricity of oil does > not last forever and heat, dirt and other contaminants will cause > wear....I promise you. > You can take a 5 spd from day one and never change the oil for 100,000 > miles, and I will will change the oil every 25,000 to 30,000 miles, if > the 5 spds are torn down, yours will have more wear and tear than mine. > The same principle works in engines...The more often you change your oil > and filter, the longer your engine should last. ken, i agree with you about engine oil. the gearbox is a different matter. no appreciable amounts of oxidizing agents are present. i seem to recall that the reason for oil breakdown is chemical, not mechanical. the high crankcase temperatures only speed the reactions. one question you might want to ask is why saab only recommends to check and top it off rather than change it on a regular basis. i think saab (or any manufacturer) would recommend changing the oil if it helped the gearbox last longer. the lack of a trans drainplug on a 9000 is possibly saab's way making it harder to change gearbox oil. there are factory transmission shop manuals for other makes that command one NOT to change the trans oil/fluid. one i can think of is the 60s chrysler torqueflite which was one of the best automatics around. (ours lasted with the same fluid for 270+ k miles and still worked fine when the car was scrapped.) i believe that some american differential shop manuals also discouraged oil changes. (perhaps they still do - haven't read one lately.) ken, fear not - no bubbles are in danger of bursting. i just know that your 'common sense' does not apply in the above cases. i do not know exactly why these recommendations are made. i just follow them and obtain great service from these components. regarding your offer for a side to side comparison - no thanks. that's saab's job and i think they've already done that. perhaps someone who is a professional authority on lubricants and transmissions can explain the likely reasons for not recommending to change the trans oil? thanks, -- ladislav
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