1979 Air cooled V1000 G5. I realise that this has probably been discussed endlessly prior to my joining the forum this week, but hope you’ll suffer my questions. With the separate gearbox, is there any need to veer towards bike specific oils, or is there a good quality synthetic car oil that people are happy with?
*** OIL THREAD ALERT ***
Problem with more car oriented oils is that they are lo/no ZDDP as that messes up catalytic converters. You want a good ZDDP content in your oil as that bike is running flat tappets. Other than that I think either a 10/40 or 20/50 will be fine.
I’ve been using Duckhams the last few years though I note that Opie are out of stock at the moment.
https://www.opieoils.co.uk/p-197323-duckhams-classic-q-20w-50-engine-oil.aspx?VariantID=303307
As there is no need to worry about it affecting the clutch on a Guzzi, I use Halfords Classic 20/50. No good in my Bonnie as it messes with the wet clutch
Thanks for the heads up relating to modern synthetics and the valve gear which had not occurred to me. I like Opie Oils except for their delivery charges. Just ordered 10 litres of Morris Oil 20/50.
Phew, we got of lightly with that one. Oil threads usually turn into a bit of a war of words
Oh no they don’t!
I don’t think you need a fully synthetic for the old bikes, semi or even mineral is probably OK if you are replacing every 2000 miles.
That said I have been through using car oil, Halfords 20x50 semi synth etc, and now back to using the recommended Agip I think. Never had any issue with any of them on my 1990 ish Lemon. Usually order from Gutsibits these days cos I is lazy…
Important thing is the gear oil…
Somersetlemon; that was going to be my next oil thread question 
Just drained all the oils. Engine oil obviously hadn’t done a great deal as was still clean and clear but gearbox and bevel came out looking like grey sludge. I will be dropping the sump to renew the filter and to give the sump a wash out BTW. None of the magnetic plugs had any accumulation of filings which was reassuring but the grey colour of the gear oils was a little disconcerting.
I have a gallon of Millers 75/90 gear oil which seems like water in comparison to EP 90 which I’ll briefly run through the box and bevel to flush out the residue of the grey stuff.
Any recommendations for the best Guzzi gear oil?
Hi Godfrey,
To put your mind at rest, and hopefully put and end to this thread before it becomes a long repetition of previous versions, I suggest you read the original manual, either Workshop or Owners, and it will tell you what was recommended by Moto Guzzi at the time. You do not need to do anything more than follow their recommendations. “Grey sludge” in the rear drive box is normal assuming the molybdenum additive was used. The gearbox oil should be clean. Changing all the oils make sense and if you are worried about excessive wear etc then change them all again after 1000 miles and see what they look then.
Hope this helps
Cheers
Phil