By Andy C
What is the concensus on oil chaneg intervals for the classic engine?

Manual say 6000 miles but given the rudimentary filtration that these engines have, changing it earlier my be a better option.

Dont want to change the oil for the sake of it.

Using 20/50 mineral oil.

I have heard the figure of 1500 miles suggested.

By sofiaspin
Done 5000 miles on Efi C5 and changed the oil and filter 4 times. I add a couple of changes up to 2000 miles because of all the crud that comes out as the engine beds in, but we also added the Vibration reduction plate and bigger front sprocket which meant an extra oil change. Just done the fourth this week plus a new battery (the original only lasted 16 months) and tyre and service. Extra oil changes help smooth down the vibes and the bike certainly seems to go much better - I will reduce frequency of oil changes now. Use hosts Silkolene 15-50
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By stinkwheel
I do mine every 1500. Not that any of the oil in it by that point is the same as it started out with from the previous service but I reckon it helps to swap out the filter to get rid of any muck.

I usually cut the filter in half with some tin-snips to see if there are any lumps in.
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By Presto
This is a regular question on the forum, but a fair one. I’m always a bit amused at the extremely short oil change intervals some users prefer. I’ve no idea what the logic is behind a 1,000 or 2,000 mile oil change may be. Modern multigrades have an extensive useful life in these very under-stressed motors. These oils would continue to provide excellent lubrication and protection well beyond 5,000 miles. This would be in-line with oil companies’ recommendations - and they have a vested interest in selling you the stuff! Some engine manufactures recommend much wider intervals, in the order of 10,000 miles plus.

Given the cost of engine oil, and the hugely detrimental environmental effects oil has before and after use, a wider change interval than many of us were brought up on may be worth considering. We moan about the cost of fuel and welcome high mpg but seem to adopt a very different philosophy over engine oil. Strange.
By sofiaspin
Fair points - but the crud that came out of my supposedly unstressed motor in the first two oil changes defied belief. Same with the GT 535 - almost sludge like - after 900 miles. I tend to push on and use available revs and gears - so it gets a good work out. At 4600 miles I am now happy to leave it for a while.
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By stinkwheel
My oil is black as sin by the time it comes out after 1500 miles.

Pretty sure the 1500 mile service interval was from the service book. Could be wrong there. I'll see if I can rake it out later on.
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By Wheaters
The service book I have for my "iron" Bullet says change the oil and wash out the oil filter at 6,000 kms.

Change the filter every other oil change.

6,000 kms is 3,728 miles.

The mineral based 20W/50 on my bike gets used as hard as I can do in a Bullet and it wasn't really very dirty after that mileage.

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