BDH Transmission Oil

[Hermit]

I recently acquired a BDH.  I found the transmission oil slightly milky so I had planned to change it.  I went looking for some SAE 40 or 50 oil with a GL1 spec using info from this forum and the manual.  I found this type of oil was difficult to locate.  Talking to a local oil distributor, he said that the SAE oil viscosity specs from the 40's and 50's need to be converted to new viscosity specs when dealing with gear oil.  He had a chart showing that engine oil with a SAE 40 or 50 viscosity index was equal to a SAE 90 GL1 gear oil.  Never having heard this before, I went to my Marks' mechanical engineering handbook.  It has viscosity index charts for engine oil and gear oil (SAE J300c and J306a) showing that SUS and Centipoises viscosity units are almost the same for SAE 40 and 50 engine oil and SAE 90 GL1 gear oil.  So my question to the experts on this forum, is it suitable to use SAE 90 GL1 in the transmission?  To me, it appears so.  Please educate me.  Thanks.

[John Schwiebert]

It is not the viscosity, but the additives in the 80-90 gear oil. Let me check in to this also but it will be at least a week before I do so.

[Blake Malkamaki]

I think Ray has researched this and I believe he said GL-1 was ok. But, you should be able to get some 50 wt non-detergent engine oil. That is what the company recommends.

Where do you live Hermit? You didn't put it in your bio. I know 50 wt non-detergent should be available in NW Pa.

[Hermit]

I have a shack in the woods of the Upper Peninsula of Michigan.  I found one oil distributor that has SAE 50 non-detergent for $37 for 5 gallons.  However, Walmart has 5 gallon buckets of SAE 90 GL1 for $24.  I'm still looking into the various service classifications for engine oil vs. gear oil.  I've found so far that there's been lots of changes in testing, classification, refining processing and additives utilized.  The actual process of changing the oil is easy but I have a terrible habit of asking "Why?".  I figure knowing more is better.  So I'm open to all inputs.

[RLH]

What is the reason for a non detergent oil? Is it just to keep the oil from cleaning?
Randy

[Blake Malkamaki]

I have a shack in the woods of the Upper Peninsula of Michigan.

Where in upper Michigan? My aunt lives in Iron Mountain.

Blake

[Blake Malkamaki]

What is the reason for a non detergent oil? Is it just to keep the oil from cleaning?
Randy

I think the detergent does bad things to the steering bands or makes them not work as they should. I have detergent oil in my E right now that I need to change out.

Blake

[walter hudson]

Ihave always used 80W90 in the trans./diff. .The only problem I have noticed is in really cold weather the steering does not work as well. Cold in tennessee is a low of 15-20 degrees ,so where you are located a thinner oil might be better.