I use a multi grade 20/50 in my P1 as it has fully floating big end shells and doesn’t have great oil pressure. The K1 on the other hand has 8 ba conrods and tagged big end shells, which gives me 50 psi oil pressure, normal running, 20 psi on tickover when hot, using multi grade 15/40 oil. This is oil with detergent added, but my K1 has a full flow spin on oil filter and I usually change the engine oil every 1000 to 2000 miles. My P1 has covered at least 60000 miles since I put it on the road back in 1996, and has just needed on exhaust valve replacing. Still going well.
I use a multi grade 20/50 in my P1 as it has fully floating big end shells and doesn't have great oil pressure. The K1 on the other hand has 8 ba conrods and tagged big end shells, which gives me 50 psi oil pressure, normal running, 20 psi on tickover when hot, using multi grade 15/40 oil. This is oil with detergent added, but my K1 has a full flow spin on oil filter and I usually change the engine oil every 1000 to 2000 miles. My P1 has covered at least 60000 miles since I put it on the road back in 1996, and has just needed on exhaust valve replacing. Still going well.