Oil Change Bukh 20 Dv

I have been using a Bukh DV20 for over 25 years - the recommended oil for this engine is SAE30 - using a multigrade won't cause any short-term problem, and is certainly better than nothing, but may, according to some sources, lead to bore glazing if used long-term.
 
Vyv, what are your thoughts regarding oil for the BW7 gearbox which the BUKH usually comes with. Manual quite specifically says "SAE20 or SAE30 (normal engine oil); MULTIGRADE SHOULD NOT be used".

I cannot see a good reason why multigrade (10/40) should not be used, and have done so ever since straight SAE20 or 30 has become difficult to obtain. No problems with gearbox ever ....apart from input/output seals which is fairly inevitable at 27years.
 
I called the thoroughly reliable & always helpful BUKH UK people last week as it does not seem easy to find SAE 30 (for my venerable, 10000 hr plus, BUKH 20) and their recommendation is to use:

15w/40 HD Mineral Oil which they say is suitable for engine and gearbox.

Presumably this aligns with Vyv's API CF spec - his advice is always spot on too!

Simon
 
I always used 15W/40 in mine. Air cooled VWs were always supposed to use mono grades only but I used multigrade in all of mine with no problems. I would not use 10W/40 in an older engine as I think the lower viscosity is too low for starting with increased clearances.
 
I would not use 10W/40 in an older engine as I think the lower viscosity is too low for starting with increased clearances.

Thanks Vyv. Checked the shed and yes it's 15W/40 (not 10W/40) that I've been using in both engine and gearbox. Tesco's mineral oil CD 'for older diesel cars'. They don't list it online, but must keep a look out at the superstore as starting to run low.
 
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