revtothelimit - motorbike forum

Right now it has my custom blend 12 1/2 - 42 1/2 in it...

1 quart of 20/50 & then bring it up to capacity 10/40, Mobil1.

ZRX61 wrote: Thu Apr 16, 2026 12:02 am

Skub wrote: Wed Apr 15, 2026 8:35 pm What was the question again?

Full synth in the '83 GPz11, ok or not?

I was advised to use mineral 20w50 to run mine in and then go to 20w50 semi Castrol once it was run in by a friend who builds race engines for a living, I think fully synthetic would be a bit thin for a roller bearing crank and also a waste of money.

Le_Fromage_Grande wrote: Thu Apr 16, 2026 10:07 pm I was advised to use mineral 20w50 to run mine in and then go to 20w50 semi Castrol once it was run in by a friend who builds race engines for a living, I think fully synthetic would be a bit thin for a roller bearing crank and also a waste of money.

I had some laying around. It's not going to be in there long.

Seen a lot of people saying to stick 20/50 GTX in it... which is odd as several years ago Castrol changed the formula & stated "don't use this new version in your motorcycle".. but apparently a bunch of people do.

Supermofo wrote: Thu Apr 16, 2026 1:38 pm A lot of people just don't bother with services from looking at this

Over here people just dump in a quart of ATF to dislodge all the snarge* shortly before an oil change, drive maybe 20 miles.

I've done it with old Ford 390 V8's, but just let it idle for 20 minutes or so. The issue is all that crap potentially blocking the pick up in the oil pan and/or the filter etc.



* USAF term for a mix of snot & garbage

I'll be sticking some Motul 5100 in it after 1000 miles or so. Peace of mind is cheap.

Many years ago I pulled into a Shell gas station in Santa Monica on a Z1 or KZ, at another pump was the rattiest XS1100 I've ever seen. Rider looked like an extra from Mad Max having a bad day.
He walks over to me & says "Could ya spare a couple of bucks for a quart of Motul?"
Great line, cracked me up, I gave him $5.

Skub wrote: Thu Apr 16, 2026 12:38 pm According to a mate in the car trade,they see lots of wagons with the top end sludged up. It seems especially prevalent among car drivers who piddle about at a maximum of 2k on the tacho. The damn things need a good thrashing at least now and again.

Long intervals between oil changes won't help sludge issues either.

It doesn't help that a lot of places don't take oil out from underneath, they suck it out via the dipstick tube. Ford/Pug 1.6 diesels die if you do that.

The only bike I use fancy oil in is the K12, the Boxers get cheapo 20w50 mineral.

Fully synthetic in 1955 Triumph.

What was the question?



I hope no-one’s trying to ride around without any Synerlec!

Go sdk a cosycolubretech

I'd use the cheapest dino oil available

Skub wrote: Thu Apr 16, 2026 12:38 pm According to a mate in the car trade,they see lots of wagons with the top end sludged up. It seems especially prevalent among car drivers who piddle about at a maximum of 2k on the tacho. The damn things need a good thrashing at least now and again.

Long intervals between oil changes won't help sludge issues either.

On holiday a few years back, we met a guy who was a land rover tech, and he said the same thing. He had a LR Ingenium 2.0 with 180k miles which had never had any engine problems. He said its because he does 6k oil changes. The LR schedule is 20k oil changes! No wonder they sludge up and the timing chain tensioner seizes, the chain stretches and death arrives shortly after...

My old neighbour was an AA man who had many sorry tales of cars. He said all modern diesels choke themselves to death with town use. He also reckoned the only diesels he'd put faith in were ones made in the 90s and early 2000s!