Q.Does oil lose its viscosity after a period of time?
I will be paying $25 a litre for oil to go in my sprint car claimed that they have had great results using it in a standard car class minis i think.
Do you think it is worth it they also said it will last for 3 years which i am not sure about at all.
Thanks russell - it's always great when us beginners are catered for. :)
I too am interested to know what happens to oil over time. In my case, it is relevant because my car is driven infrequently and I'm worried that oil that is months old may be less effective when the car does get driven.
Jack Travis, E-Series Acting President
1989 Ford Fairmont Ghia turbo/GL replica (underway)
1994 Eunos 800M
1990 Ford Laser S
I will post a more detailed explanation of oil durability and frequency of changes but to answer your questions quickly - oil suffers three things that harm it's efficiency (especially mineral based ones) -
1. Contamination from unburnt fuel (especially if you do a lot of short trips), carbon deposits and micro particles of metal from normal friction wear.
2. The heating and cooling cycle also gradually decreases the efficiency of engine oil as it graduallay breaks down the base materials.
3. If left for extended periods of time oil will also start to separate into the component materials - this is especially so if it is heavily contaminated with unburn fuel.
I saw a new Ford Mustang at the ultimate holden and ford show last night after i parked my car in the show at the falcon car club display and i tell ya, you are right about the Mustang
For a sports car the Mustang has a piss poor interior and very slack build quality. Yanks still use keys to open the doors rather than the push button pad.
Horrible light grey color too
The Camaro SS ain't much better either.
If i ever get to buy an american car i will go for a Dodge or a Pontiac F/Bird.
Who was the a**ho** who made Ford and most car manufacturers go away from the jet black interior for sports cars.
My AU interior is grey too but i have had some of the seat cloth changed to galaxy blue and it's better cloth than what goes into HSV's
have also got some galaxy blue paint from a panel shop and painted most of the centre console,interior plastics and now plan to paint bits of the engine bay,
Looks killer. Just wish i could post photos.
Just one clarification: a multigrade oil will still seem to lose viscosity (it becomes thinner) as it is heated, it's just that it does so slower than a single grade. A 40 weight oil at 500 degrees is still going to be thinner than a 5 weight oil at say 50 degrees (using arbitrary figures here).
As for oil usage and life, one of the major killers of the oil package (consisting of base oil and any additives/modifiers) is water. Water will use up the additive package and eventually will form acidic compounds. This can be tested by looking for a 'Neutralisation Number' which tells the tester whether any water combatting oil additive remains. Even if water is evaporated out, it has still depleted the additives and so more oil changes are necessary.
Engines running diesel fuel can suffer more dilution of the oil especially on short runs and so many diesel engine operators are using micro-filtration to remove the water and diluting agents.
Oil itself can last a long long time. For example, in jet engines the oil is never changed (except at rebuilds) because as oil is used it is topped up and the additive package is sustained. As long as this additive package is intact the oil is providing the required protection. Good filtration adds to the life of the oil.
Well done mate. Keep it up.
BA'1.5' Pursuit 290
Lightning Strike / Reflective Orange Stripes 'General' Dog - AP's German Shepherd and Best Mate - 02Dec1998-15Dec2003.
'Pepper' Dog - General's and My Little German Shepherd Sweetie - 1996?-02Apr2006. 'Sako' Dog - My Beautiful and Pretty German Shepherd - 2001?-23Aug2006.
Very informative reading mate. Ok just once question am i right in saying that a 5w-30 and a 10w-30 are the same viscosity when the engines are at operating temperature?
If so then my dads theory on oils is right go for the widest reading ie 5w-50. I often hear people saying that Mobil 1 5w-50 is too thin, but if the top number is a 50 then is no thicker or thinner than any other oil with a w50 rating.
Motor May 2001 Quote: "Believe it or not, there are actually a bunch of weirdos out there who reckon a six cylinder is the dux gutz. Bugger it: I'm one of them" :s5
AUII Late Ed XR6 HP T5 Venom- Full Tickford Body Kit, 17in Wheels, Herrod Bi-plane Spoiler, Momo Steer/Gear, T-Series Interior Options, Premium Stereo and a very light-tuned 4.0L I6
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Strider - effectively you are right but the top weight must be within the manufacturers range of tolerances - an oil that is too thick (for want of a better term) will not flow to the engine parts as well as a thinner one might. Likewise while a 5W oil will get to engine parts quicly when the engine is cold it may not provide sufficient lubrication when it does.
It is all compromises.
For those requiring further info please see the Oils 2 thread posted tonight.
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