octane rating for r80rt

[scurry0]

Speaking of Octane, Is it true that one should add a 'lead" product to the fuel for an older, (1973 R75/5)?
I can only get gas that is allegedly 10% ethanol.
According to the BMW manual, leaded , high octane fuel (93) should be used. Any ideas on this?

[20774]

In general, adding some sort of lead enhancer only lightens your wallet. The only true fix is to perform a top end. At some point, you'll need to do the pushrod tube seals, and that would be the time to send the heads off.

The plan at this point would be to set the valve clearances (I recommend 0.15mm intake and 0.20 exhaust) and then monitor the clearnaces at 5K miles intervals. If they begin to close up significantly and you're now starting to check every 1K miles, you've probably reached the point of concern. And any additive probably won't have saved you by much...maybe added another 10% of so??