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Model specific boards => Golf mk3 => Topic started by: snifferdog on 25 February 2010, 16:59
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I was thinking of servicing the mk3 this weekend and was gonna buy some oil, but i just looked in my shed and found an unopened bottle of castrol gtx 15w40, dunno how long its been there, probably, say 8 years. The label has come off the back at some point so i cant read if it says what engines it would be good for etc. what i want to know is will it be any good for my golf? Its a gti 8v. Cheers. :smiley:
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it will be fine
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Cheers mate, just thought id check cos i was gonna buy 10w40 and i dont really know what the numbers mean,haha. :grin:
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w stands for weight. so 15w is thicker than 10w ect. 15w is better for cars that have covered some miles.
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If it has been in the shed for 8 years I would bin it.
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w stands for weight. so 15w is thicker than 10w ect. 15w is better for cars that have covered some miles.
Actually the W doesn't stand for weight. It stands for Winter and indicates that the oil has had it's viscosity (thickness if you like) tested at low temperatures. The 0, 5, 10, or 15 is then a viscosity index or 'grade' based on that low temperature test. A 5W30 will be thicker at 0C than a 5W30, but they will have roughly the same viscosity at 100C.
The 30 in 15W30 indicates the viscosity at high temperature (100C) and as mentioned will be more or less the same whether it's a 0W30, 15W30 or something in between.
A 15W oil will be thicker at low temperature than a 5W or 10W. This is not necessarily good for an old engine, which arguably requires cold oil to flow just as easily as a new engine at start-up. If you are talking about an engine from the 1930's then it might be a different matter, but any VW watercooled engine (i.e. from the 70's onwards) will be fine with a 5W or 10W oil. I'm not saying don't use a 15W if you are happily using one.
As for using an 8 year old oil, you should consider that the additive packages deteriorate with time, through oxidation and other chemical changes, as well as separation. Sediment and waxes can form, the viscosity index of the oil will change and then there is the risk of moisture contamination (even in a sealed container). The oil may look alright, but it probably isn't. When your engine gets hot, or when it is starting from cold it won't provide the protection of new oil. It certainly won't last as long.
Wayne is right - bin it.
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makes you wonder why the book says use 15w if you have high mileage. :huh:
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The higher viscosity of 15W oils at low temp means they are less likely to seep past old piston rings or valve stem seals that are less than perfect while the engine is switched off - which can result in that puff of blue smoke on start-up. But the biggest benefit to high mileage engines (where tolerances are increasing due to wear) is the extra viscosity at higher temp - so it's more the 40 in 15W40 than the 15. Some oils marketed as made for old engines may also have additional EP and anti-wear additives which can help a little.
A 15W might also be slightly better for the cam lobe/follower contact points on start up but I thinnk it would be worse for hydraulic lifters, which like low oil viscosity to allow the lifter to "pump up" quickly when cold. I personally think 10W40 is better for most 70's-90's normally aspirated VW engines, even high mileage ones. I drove a Mk2 just under 100,000 miles from new on 0W40 synthetic oil. When we stripped it down there was virtually no wear.
I forgot to mention - as a general rule shelf life for motor oils is 2-3 years.
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Cheers for the help peeps. Think i'll be binning the castrol out the shed then! :grin:
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:embarassed:
Yeah I think you should to.
Cool I understood oil numbers, well so I thought. I now have a better understanding of them lol. cheers for that dude.
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I used 15w-40 mineral oil in the mk2 and now use 10w-40 in the mk3. Doesn't really matter what oil you use as long as it's not too thin or else the old seals and worn piston rings will let oil through. 10w-40 is about right for a mk3 golf.