Oil question Castrol GTX 20W 50 vs Castrol Grand Prix 20W 50

I have heard some reports here from local bike owners that Castrol turns to as thin as sewing machine oil and then engine starts to eat it away, probably leaking from piston rings or valve guides. Some reports are from 40 years ago and some are from last year. I'm not going to underwrite anything about this, because there are too many other factors.

redfox said:
Not sure what you ask about MotoJouni?
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I didn't understood what is regularly at the minimum if the engine is not using oil?
I'm adjusted to that the oil level should be at the same level where I filled it on previous change when I'm draining it out (mostly it is), no adding oil on normal changing intervals.
 
After breaking the freshly overhauled engine in, oil consumption on my 3C has settled at around 200ml/1000k's (20-50 mineral). I'd consider this as normal for such kind of air-cooled engine with no valve stem seals on exhaust valves. The bike has no oil cooler, nevertheless, I only use it from cold on rides exceeding 50 k's, leaving the city limits behind, so oil gets on temperature for a considerable amount of time.
With no oil consumption during the 2500k change interval, I'd be rather concerned about a too rich mixture or improper riding habits. AFAIK more or less any engine oil will suffer a drop in viscosity when enriched by condensates, but there might be grades that are less or more sensitive?
 
As much as we can say we don't like this or that oil, whilst not my choice, Castrol is good quality stuff, fully tested to SAE etc.
It's probably more about suitability to our dinosaur engines than anything else; I can't see the oil breaking down any faster than
anything else grade for grade; Castrol have been at it for years?

There's a looooong running thread on Piston heads by Opie Oils, if you post your application there, he gives very sound and un biased advice and explodes a few myths along the way too. Although primarily a car oil topic, he does cover bikes too; worth a look if you don't have an habitual 'OK' oil of choice like me!


http://www.pistonheads.com/gassing/topic.asp?t=237643
 
I think that's the way it should work. Upper piston rings and valve guides got their lubricant from that small amount of oil passing to them. That's why even valve guide grommets are designed to leak certain amount and cylinders are honed to carry oil.

I have used quite much Silkolene Pro 4 on bikes and Pro S (Fuchs Titan Race today) on cars. It's very interesting IMHO that most engines don't seem to use these at all, but also the wearing almost stops. Same thing for first runned-in engines or even very loose engines that need to be refurbished. Also breathing has stopped practically saying. Same engines do eat some (or even much) mineral oil, but I use it mostly for running in.
 
Dingocooke said:
http://www.pistonheads.com/gassing/topic.asp?t=237643
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44 Pages on an oil thread. We really do have to pick up our game.

Actually some interesting reading in there, particularly regarding additives, once you filter out all the repetitive questions.
 
Because fully synthetic ( not the faux synthetic chemically altered mineral oil) does not come out of those barrels.
 
MotoJourni: I meant that I change the oil minimum once per year or more often with regards to milage, whatever comes first.
On my cars, i use the newish TI-version of the Castrol oil, and it's Wear rate is certainly better than most if not all. I called Castrol UK and asked them lot's of questions on this new oil.
I await some stuff to be developed for ould two wheelers as well.
Anyway, I have nothing against castrol oil.
Just my two pence.
Jacques.
 
^Thanks for the responce.  I misread your sentence :) And happy Xmas

Personally I change oil to cars at wintertime every 7000-8000km if the colour is still ok. Summertime every 8000-10 000km if the colour is still ok. Many times short distance driving or if last oil change was a littlebit late the next change would come earlier, but it is indicated by colour of oil. I don't care manual says this should be longer. Also I maintenance spark plugs every 7000km to 8000km on my cars, replacing every second time, no matter what the manual says. This seems to be the longest interval keeping the engines run perfectly on my cars. I don't ask in surprise that many new cars burn ignition coils, if maintenance interval is for 50 000kms and the spark plugs have 3mm's of gap then.

I'm interested to see how much is the oil consumption on my 1000 SFC engine I rebuild. Next summer it will go over 10 000km after rebuild and I'm going to change full ester oil, Pro 4 on it.  :)
 
Hi MotoJouni,

When i was talking to Castrol UK, they said some interesting Things, for example that new engine oil should not be poured into an engine, and then it's stored directly for the Whole Winter, or for any other period, for that matter.
They explained that the additives in a new engine oil can be a Little agressive to anything it get's in contact eith. Therefore they advised that after changing oil, one should either drive the motorcycle/car/? for a good long trip, or let the engine run for a while in idle, then sore it.

Kind regards,
Jacques.
 
Paul LeClair said:
I am about to tackle oil changes on 5 of the 8 bikes in the garage.

Castrol has an oil they sell for cars as Castrol GTX 20W 50, and an oil they sell for motorcycles as Castrol Grand Prix 20W 50.

Can anyone tell me if there are any significant differences between those two Castrol oils, other than price?

Paul LeClair
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  Hi Paul,
      The Castrol Grand Prix 20w-50 has a higher sheer viscosity capability, hence it's API spec "SG" rating. SG rating indicates it also has higher zinc, phosphorous, and other extreme pressure additives for gearbox lubrication, not found in modern 20w-50 oil of API spec SJ and later.
I use Castrol GP 20w-50 SG or Pennzoil 20w-50 SG on my Laverda, and change the oil at 1600kms.
 
According to their website, Castrol GTX 20W50 for cars has a SM API rating, which means it has "friction modifiers" in it (among other things) and is not recommended for wet clutches. Actually, to quote the website, they say it "may affect the performance of wet clutches"



 
Dellortoman said:
According to their website, Castrol GTX 20W50 for cars has a SM API rating, which means it has "friction modifiers" in it (among other things) and is not recommended for wet clutches. Actually, to quote the website, they say it "may affect the performance of wet clutches"
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  Correct. API spec SG is the rating North Americans should be looking for. Or JASO MA, or JASO MA2. 
  API [American Petroleum Institute] is not found sometimes in Europe, hence the difficulty in oil recommendations from bike enthusiasts around the world.
 
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