Why change your oil?

[F5 Dave]

. . . Those guys are fucking passionate about viscosity.

I like going fast too

[Laava]

Haha Dave!😆😆

[Paul in NZ]

To me the answer is - it depends... I regularly change the oil and I don't for a second think the extended servicing times on my Mazda 6 are realistic. You can literally smell when the oil needs changing so I change it.. 10K is about as far as I let it go and usually around 7K


My observation is that some vehicles need the oil changing much more frequently that others. If the engine oil is shared with a primary chain or gearbox then it should be changed frequently. The ancient Triumph shares oil with the primary and its fucked in 1000K.

[roogazza]

Modern quality oils don't break down like olden day oils. (as much as .)
We change them cos they get dirty.

[Bonez]

Modern quality oils don't break down like olden day oils. (as much as .)
We change them cos they get dirty.

Can you even get castor oil these days? That'd be a Anoraks wet dream.

[F5 Dave]

Castrol R40, yes you can. Favoured for its film strength under extreme conditions.

[Bonez]

Castrol R40, yes you can. Favoured for its film strength under extreme conditions.

Fucken hell it has extra "oilyness" as well. Does the mean it's oilier than mineral and synthetic oils?

[Blackbird]

As others have said, synthetics or semi-synthetics have a better useful life than mineral based oils. Also, performance is a much slower decline than the more abrupt decline of mineral oils. Our large company vehicle fleet used Mobil multigrade oil and when Mobil 1 first came out, we did some comparison tests. From memory, the amount of wear debris in the oil for Mobil 1 was about half that for multigrade (EMPA spectroscopy). Trouble was, Mobil 1 was massively more expensive at that stage and it was more economic to continue to use multigrade with more regular changes.

I experienced the downside of synthetics first hand. I was able to buy Mobil 1 at a substantial discount through the company and stuck it in my wife's first MX5. Her car had done about 80,000k at the time and the excellent scavenging properties of the synthetic oil caused the engine seals to weep once the carbon and other deposits were flushed off.

I guess that you can boil it down quite simply. Tyres and oil are critical on a bike, albeit for different reasons. Makes sense not to skimp on either.

[pete376403]

Castrol R40, yes you can. Favoured for its film strength under extreme conditions.

I used to run Shell Super Heavy in my speedway bikes. It was castor, not quite as good as r40 but about half the price. would get a full season out of a crankshaft so it did the job. Still had the same beautiful aroma when burned with methanol and still made the same gummy mess if left to oxidise.

Later I switched to running Rimula X50 and the crankshaft lasted just the same, much cleaner

[husaberg]

Castrol R40, yes you can. Favoured for its film strength under extreme conditions.

A747 also had in some castor. All the 2t GP bikes used to run castor despite what the sponsors stickers said pretty sure it was Castrol as well in most cases
i understand the beans shell makes a pretty useful poison as well, Also according to google the oil is a decent birth control...... WTF

[Grumph]

As others have said, synthetics or semi-synthetics have a better useful life than mineral based oils. Also, performance is a much slower decline than the more abrupt decline of mineral oils. Our large company vehicle fleet used Mobil multigrade oil and when Mobil 1 first came out, we did some comparison tests. From memory, the amount of wear debris in the oil for Mobil 1 was about half that for multigrade (EMPA spectroscopy). Trouble was, Mobil 1 was massively more expensive at that stage and it was more economic to continue to use multigrade with more regular changes.

I experienced the downside of synthetics first hand. I was able to buy Mobil 1 at a substantial discount through the company and stuck it in my wife's first MX5. Her car had done about 80,000k at the time and the excellent scavenging properties of the synthetic oil caused the engine seals to weep once the carbon and other deposits were flushed off.

I guess that you can boil it down quite simply. Tyres and oil are critical on a bike, albeit for different reasons. Makes sense not to skimp on either.

Late 80's a customer got a Mobil 1 sponsorship - basically some decals and about 60L of oil. He moaned to me about how fast he was using it. On enquiry, it turned out he was using it in his van as well as the race bike. I basically smacked him upside the head and said " by all means use it in the van - after it's been through the race bike, dickhead "

[husaberg]

Late 80's a customer got a Mobil 1 sponsorship - basically some decals and about 60L of oil. He moaned to me about how fast he was using it. On enquiry, it turned out he was using it in his van as well as the race bike. I basically smacked him upside the head and said " by all means use it in the van - after it's been through the race bike, dickhead "

Britten bike waas sponsored by Mobil 1 and according to a blurb the ever the salesman wrote it apparently worked "so good" they had considerable trouble bedding in the rings, I wondered if the likely cause was that cause it had forged pistons with decent clearances with liners they couldn't stop it smoking on startup. So that was the given excuse.
I wonder how thr F1 guys stop that? i guess with the coated liners the clearances are far smaller than the cast linered Britten.
I remember that the late UK supermono champion David Morris mentioning in a mag he used to have to use cast pistons so his high brow sponsors didn't get the wrong idea about professionalism of the BMW Bike as it woyuld smoke on start up in the pits.
Personally i used Mobil 1 for years for gearbox oil as it was the cheapest synthetic , everyone used to go on about how it would make the clutch slip,yeah right, not sure it was better than Castrol Grand Prix.

[Grumph]

The Britten ring problem wasn't the oil. I'd put John onto using a real reed valve on the cases - actually the common 4 petal RD/DT assembly. It worked, the oil stayed in the motor. Later staff convinced him to use a big PCV valve. It was not as sensitive to the oddball case pressure variations of a 60deg V twin.
I was told that the PCV equipped customer bikes were hell on the dyno trying to bed the rings.
The "works" bikes all have the reed block in a CF pyramid on top of the cases.

[husaberg]

The Britten ring problem wasn't the oil. I'd put John onto using a real reed valve on the cases - actually the common 4 petal RD/DT assembly. It worked, the oil stayed in the motor. Later staff convinced him to use a big PCV valve. It was not as sensitive to the oddball case pressure variations of a 60deg V twin.
I was told that the PCV equipped customer bikes were hell on the dyno trying to bed the rings.
The "works" bikes all have the reed block in a CF pyramid on top of the cases.

Pretty sure i have seen the PCV but never the Reed.
Havin a closer look it looks like there was at least three versions
i cant find a decend pic

the one that has the best pics is the one from Performance bikes with the engine in a million pieces
but the version i remember is the one here the similar to the singles one.



third pic in this line looks like they rested an intake trumpet on it.

[actungbaby]

Motorcycles in main oil is shared with the gearbox .so gears over time break down oil .it's up to each person to decide .what I read synthetic oil is better for anti share .from memory.
Air cooked engines be more demanding .also heat range is important. Esp lower range keep right viscosity.when your got two bearing surfaces which suspended on thin oil film .it's good to have best possible
Condition oil.of course if it's old banger or lawn mower

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