Which is better, synthetic oil or semi-synthetic? Can you swap between the two? Can you mix the two? If not, why not?

I have been warned off fully syn for an R1 because of clutch slip but semi-syn seems the way to go.
The advantage of syn oil is higher temp before it is fried.
As long as you totally drain an engine, using either is ok.

[Edited on 23/4/2007 by nitram38]

Don't really know which is better but considering we change the oil every few thousand miles, it would become quite costly if using fully synthetic. Needless to say we use semi-synthetic and haven't had any issues thus far.

Phil

Oh jeez, not this one again

As long as you use bike specific oil, then fully synthetic is fine, the only people who seem to advise against it because of clutch slip are the ones who heard it from someone else, who invariably heard it from someone else, who invariably heard it from someone else

Between myself and ~5 trackdays mates with various BECs, over the last 5 years we've done well over 100 trackdays and probably 30k miles between us (not each!). We all use synthetic bike oils of various flavours (Castrol R4 Superbike, Mobil1 4T, Redline 10/40 etc) and I don't think any of us have ever had a clutch problem relating to oil.

Although its obviously best to stick to a single brand, oils can also be mixed without issue. If you think about it, they have to really because short of dismantling an engine for each oil change, you'll always leave a reasonable amount in there when you drop the sump plug.

"Semi" synthetic (which actually marketing jargon as I thinhk they are still based on mineral oil basestocks) is absolutely fine too though, the only time I think fully synthetic may have a significant advantage is, as mentioned when temps get very hot (ie 120c+), or maybe if you had a smidge of surge and the engine momentarily dropped oil pressure, where it might protect the bearings for a little bit longer.

cheers

Chris

[Edited on 23/4/07 by ChrisGamlin]

Yup- I also heard that semi-synthetic is actually marketing hype. It just means good normal stuff rather than what it suggests (eg a blended mix of normal and synthetic oils).... Fully synthetic oil is good but expensive...... Dillema!! I suppose it depends on your engine- my old 1990 ST can use more historical oils

I've put Castrol GPS semi-synthetic in my 'blade engine. Mainly because that's what Andy Bates (AB Performance) recommended to use and if its good enough for him - then its certainly good enough for me!
One thing I have noticed with modern bike engines - compared to those of twenty odd years ago, is the extended time between oil changes.
Haynes manual recommends an oil change for the 'blade every 8000 miles.
If my memory serves me well, I'm sure for my old Kwacker Z650 it was every 1500 miles!
So although modern oils are a lot more expensive, you don't have to change them as frequently! ('Though I'm sure with the extra work it'll do in a BEC, I'll change the oil a lot sooner than 8000 miles!)

Andy.

As I said before, my R1 gets bike-specific Motul 300V either 10/40 or 15/50 (depending on what my friendly Yamaha dealer has kicking about at the time). It gets changed every spring and costs about £30-35 (plus a litre or two through the year). I get a good deal though as I buy lots of bits for my TZ250 from him.

Is it worth saving a tenner on the most important part of your engine, especially as you do trackdays?

[Edited on 23/4/07 by Coose]

I've previously used Castrol GPS semi synthetic but the 3 branches of Halfords near me have stopped selling it. I was just wondering if there is a reason not to use fully synthetic. The extra £5 a can is not the problem, I just want to use the right stuff.

Ahhh, right-ho. Nope, there's no reason at all not to use a bike-specific synthetic. The only time it's best not to is if you're running in a new motor - synthetic is that good that it can slow down the running-in process!

quote:

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Originally posted by andrew.carwithen
I've put Castrol GPS semi-synthetic in my 'blade engine. Mainly because that's what Andy Bates (AB Performance) recommended to use and if its good enough for him - then its certainly good enough for me!
One thing I have noticed with modern bike engines - compared to those of twenty odd years ago, is the extended time between oil changes.
Haynes manual recommends an oil change for the 'blade every 8000 miles.
If my memory serves me well, I'm sure for my old Kwacker Z650 it was every 1500 miles!
So although modern oils are a lot more expensive, you don't have to change them as frequently! ('Though I'm sure with the extra work it'll do in a BEC, I'll change the oil a lot sooner than 8000 miles!)
Andy.

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Well I'm going to extremes with my oil change ritual!!!
Changed the oil and filter as soon as I got the engine (2001!!!), didn't run it for a while after the first SVA test.... So prior to the 2nd test (after all of 20 miles- but 3 years!!) I changed the oil and filter again...
Now the clutch is knackered so it'll be yet another load of oil!!
I think it'll be the third oil change in 400 miles!!! LOL!!
Does anyone re-use the oil out of the drip tray??? Seems a shame to chuck it after 4 months and 300 miles....

Yes, I put it in the oil can and oil squeaky hinges with it. If it's that clean you might save a bit by using the filter again but for a once a year job it's not going to break the bank to replace them both. Why replace the oil along with the clutch? You won't lose it so just top it up.

On a BEC isn't it a wet clutch? I though if you remove the clutch cover all the oil will come out?

Not all of it as the clutch itself doesn't bathe fully immersed in oil. Depending on the height of the clutch cover / engine design, you can sometimes actually get away with jacking the car up and so tilting the engine back so you don't lose any oil.

Most excellent! Looks like a top-up post clutch change might just be in order!!!! The car will be jacked up anyway to allow me access to the clutch.... Cheers peeps!!!

quote:

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Originally posted by ChrisGamlin
Not all of it as the clutch itself doesn't bathe fully immersed in oil. Depending on the height of the clutch cover / engine design, you can sometimes actually get away with jacking the car up and so tilting the engine back so you don't lose any oil.

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For those of you that change the oil at very regular intervals, it may be worth checking out opie oils at http://www.opieoils.co.uk for some significant savings.
As a 'member' (due to being signed up to the main Tiger owners forum) I got a further discount and free delivery for a 'bulk' order (i.e in my case, 2 x 4 litres of Castrol GPS)
It also comes very quickly (approx. 2 working days)

Andy.

quote:

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Originally posted by smart51
On my R1 engine, you don't need to tilt the car, the clutch cover is above the oil level.

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