Hi Folks,
Could anyone tell me what the main advantages of using semi or fully or semi sythetic oil over a standard grade oil.
Cheers
Andy
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From the last paragraph of the "Oil Specification & viscosity Info" sticky post at the top of the page:-
"all oils ?shear? or thin down with use and this means that an oil that started life as a 10w-40 will with use become a 10w-20. The period of time this takes depends on the type and quality of the oil. The most ?shear stable? oils are proper Synthetics, either PAO (Poly Alph Olefins) or Esters which have very high thermal stability. They are in general of the more expensive variety but last longer and give the best levels of protection."
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Longer life, less wear and better fuel economy to name a few.
Cheers
Simon
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All of the above and not spending time wondering or worrying if you wouldn't have been better off using the semi or full synth in the first place.
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Many years ago, it was a big no no to mix Castrol R (which I believe was a vegetable oil) and a mineral oil. I think you had to give the engine internals a complete cleanout if you wanted to change from one to the other. BUT - is it OK to mix mineral, semi-synthetic and synthetic oils, assuming they are of the same viscocity grade? By this I mean either at the oil change (because you haven't got enough of the one type) or when topping up.
Thanks Waino
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Waino
Yes, you can mix mineral, semi-synth etc if you want to, and in fact the grades are not that important either. This won't cause any immediate problems - they will mix and there won't be any undesirable reaction between them.
It does mean though that the benefits of the 'better' oils are diluted by the 'less advanced' oils. So, where an engine needs a very specific oil (eg PD VAG engines) then a small top up with the 'wrong' oil is probably OK, but large scale topping up with the wrong oil isn't. Same goes for engines designed for the specific long-life oils.
If the engine is less critical on oil spec then mixed oils won't be a big problem.
JS
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JS - Many thanks for your reply. The specific situation that I had in mind was that I have about 2L of Halfords 'Premium' 10-40 4stroke m/cycle oil left after the last change (The bike holds about 3L) - and I believe that this particular mineral oil has now been discontinued. I was wondering what the best option was for adding to it at the next change. The bike is a 14 yr old Suzuki 500E, not a high-performance job.
Waino
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Waino
Sounds like the oil isn't that old, and is presumably the correct oil for the bike. So, use it with a litre of the current 10/40 4 stroke m/c oil that's replaced it and you shouldn't go far wrong.
JS
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Many thanks. How much longer could you extend the oil change intrervals by using semi or fully synthetic oil as opposed to a standard oils.
Edinburgh Andy
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Andy
Check out several of HJ's FAQs 3 and 5. Also, visit:
www.bobistheoilguy.com/
tinyurl.com/e3ei
On the second site (I think) and certainly in other places, I've seen stern advice against downgrading from fully synth to semi-synth or mineral oil. The sources of such advice know much more than I do, so I believe them.
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