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IMHO...... Posted by Kevin K [Email]  (#374) [Profile/Gallery]
(more from Kevin K) on Mon, 16 Oct 2000 23:06:01
In Reply to: Why is it bad to go from gear oil to motor oil in a tranny?, Phillip, Mon, 16 Oct 2000 16:43:48 Members do not see ads below this line. - Help Keep This Site Online - Signup |
These tran's were designed for ~100 hp in the late 70's, and never were properly strengthened in years that followed. Same pinion bearing there thru M88. Failures occur relatively often, and any related recent change is often labeled as an absolute cause. Motor oil on gear oil is one of these. And some of the rationalized hear-say explanations are entertaining.
At worst, this sequence may loosen up some soluble build-up on the case, due to detergents now present. This build-up is minimal, vs in an engine with blow-by, and carbon deposits related to combustion, etc. It will not result in chunks of your reverse gears that lay in the bottom to suddenly toss about, any more than they did before with gear oil.
Honda may now be 1-up on MTL. The Honda Manual Transsmission Fluid, MTF-7289, has been found to improve shifting in NSX's, vs MTL. It is a new 75-80 GL4 gear oil developed by Honda for optimal shifting. I gauge there credibility based on how they stepped into F1 and dominated the field.
POINT IS ...... they specify that if MTF is not available, use 10-30 motor oil until the MTF can be conveniently installed for optimal shifting.
Also note that Saab spec'd both motor and gear oil thru the 900 classic run, and I have never known of any saab documents discouraging 'motor after gear oil' in the box.
I do prefer some purging between changes. I'm more concerend about changing among widely varied synthetic gear oils ... diesters, PAO's, etc. To clense the pallet between courses of Redline 75-90NS (yuck) and 75-90 Neo HD, I put in 3Q's of 20W non-detergent compressor oil, and driving w/o a heavy foot a few days. I just wanted plain oil of proper vicosity to be the buffer. Much better shifting on the 20W!. I use a short length of very thin wall 3/4" alum tube (.025" thick), flatten one end to about .2 inch, then use it as a mini-funnel to run some oil thru the primary case too, by way of the snap on inspection cover.
A more sane purge is just run a month or so on the 'new' oil, then change.
just another opinion.
, Mon, 16 Oct 2000 23:06:01 <-- Viewing This Message, Tue, 17 Oct 2000 11:22:20
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