Discussion
k15tox said:
no dont mix grades, your fine mixing brands though. aslong as they are the same viscoisty and sythentic
I think you may have that the wrong way round...Mixing grades, as long as they're the same brand, is fine and you should end up with an oil that has viscosity characteristics somewhere between the two grades that have been mixed.
However, mixing brands is most probably not a good idea, as they may well contain different additives that could react with one another causing you all sorts of problems.
In summary:
Mixing brands bad, mixing grades good.
And obviously, don't mix fully synthetic with anything other than fully synthetic.
MC.
MC said:
k15tox said:
no dont mix grades, your fine mixing brands though. aslong as they are the same viscoisty and sythentic
I think you may have that the wrong way round...
Mixing grades, as long as they're the same brand, is fine and you should end up with an oil that has viscosity characteristics somewhere between the two grades that have been mixed.
However, mixing brands is most probably not a good idea, as they may well contain different additives that could react with one another causing you all sorts of problems.
In summary:
Mixing brands bad, mixing grades good.
And obviously, don't mix fully synthetic with anything other than fully synthetic.
i stand corrected!
MC.
SimonV8ster said:
I'm not sure mixing grades is that good though is it ??!!
I thought you could mix one way but not the other - as in you could put thinner into thicker or vice versa ??
(and then change it all anyway.........)
I believe (based on my limited chemical knowledge!) that mixing different grades of the same brand and type of oil, will have little or no impact on the engine whatsoever, so long as the grades being mixed are close to the manufacturers recommended specifications.I thought you could mix one way but not the other - as in you could put thinner into thicker or vice versa ??
(and then change it all anyway.........)
What you have to remember is, as soon as an engine is started the oil that is being used to lubricate it will start to break down and its properties change, including its viscosity. I'm sure you've seen the difference between the old oil that gets removed during a service and the new oil which replaces it. This difference is evidence that the oil has been breaking down and changing at a molecular level (as well as it picking up soot and metal particles from the engine), and so naturally its lubrication properties have been changing as well.
This change is relatively minor with modern fully synthetic oils but so is the change from a 5W30 to a 5W40.
I don't think there is a one way mixing rule, but I assume it stems from the idea that almost all of the bearings in an engine rely upon a thin film of oil being created between their two surfaces. As if the oil is too thin, then the layer of lubrication may not be able to be created or it would be too thin, and if the oil is too thick again the layer may not be able to be created or it would simply cause extra drag and load on the moving components. Either way, it would be a very bad thing for this to happen and I suspect you'd notice it quite quickly.
That being said, with a relatively standard GM LS engine, I don't think there's too much to worry about as the bearing tolerances and oil film thickness will be relatively large. It normally only becomes an issue on high speed, highly stressed engines such as those found in racing. In which case, a grade too thin or thick could have serious consequences.
With all of that said though, I'd always recommend that people keep some spare oil of the correct grade at all times, as we all know how much these V8's can use!
MC.
baptist said:
Checked it stone cold this morning, about 3/4 the way up so didnt need any afterall.
lol
Good discussion though. I honestly dont think you'll get any issues mixing viscosities, I know you arent supposed to blend synthetic and non synthetic though.
Where's oilman when you need him.
lol
Good discussion though. I honestly dont think you'll get any issues mixing viscosities, I know you arent supposed to blend synthetic and non synthetic though.
Where's oilman when you need him.
one mistake i have made is checking it from cold as it always reads less, then i topped it up with a little oil and checked it when it was hot, turned out i overfilled it! not by much so no harm done i think.
k15tox said:
baptist said:
Checked it stone cold this morning, about 3/4 the way up so didnt need any afterall.
lol
Good discussion though. I honestly dont think you'll get any issues mixing viscosities, I know you arent supposed to blend synthetic and non synthetic though.
Where's oilman when you need him.
lol
Good discussion though. I honestly dont think you'll get any issues mixing viscosities, I know you arent supposed to blend synthetic and non synthetic though.
Where's oilman when you need him.
one mistake i have made is checking it from cold as it always reads less, then i topped it up with a little oil and checked it when it was hot, turned out i overfilled it! not by much so no harm done i think.
ooohhh.....I always thought it was best to top up from cold as all the oil is at the bottom of the engine (truer reading of oil amount) and if warm then its spread around the engine. Lucky i haven't blown my ring.(s)sneakygloworm said:
k15tox said:
baptist said:
Checked it stone cold this morning, about 3/4 the way up so didnt need any afterall.
lol
Good discussion though. I honestly dont think you'll get any issues mixing viscosities, I know you arent supposed to blend synthetic and non synthetic though.
Where's oilman when you need him.
lol
Good discussion though. I honestly dont think you'll get any issues mixing viscosities, I know you arent supposed to blend synthetic and non synthetic though.
Where's oilman when you need him.
one mistake i have made is checking it from cold as it always reads less, then i topped it up with a little oil and checked it when it was hot, turned out i overfilled it! not by much so no harm done i think.
ooohhh.....I always thought it was best to top up from cold as all the oil is at the bottom of the engine (truer reading of oil amount) and if warm then its spread around the engine. Lucky i haven't blown my ring.(s)thats what i thought, but it states warm in the handbook, allowing 15mins for the oil to settle. if youd blown your rings you'd notice by now. without starting another debate im sure our engines are fine with an extra litre in. anymore that that and id start worring.
k15tox said:
sneakygloworm said:
k15tox said:
baptist said:
Checked it stone cold this morning, about 3/4 the way up so didnt need any afterall.
lol
Good discussion though. I honestly dont think you'll get any issues mixing viscosities, I know you arent supposed to blend synthetic and non synthetic though.
Where's oilman when you need him.
lol
Good discussion though. I honestly dont think you'll get any issues mixing viscosities, I know you arent supposed to blend synthetic and non synthetic though.
Where's oilman when you need him.
one mistake i have made is checking it from cold as it always reads less, then i topped it up with a little oil and checked it when it was hot, turned out i overfilled it! not by much so no harm done i think.
ooohhh.....I always thought it was best to top up from cold as all the oil is at the bottom of the engine (truer reading of oil amount) and if warm then its spread around the engine. Lucky i haven't blown my ring.(s)thats what i thought, but it states warm in the handbook, allowing 15mins for the oil to settle. if youd blown your rings you'd notice by now. without starting another debate im sure our engines are fine with an extra litre in. anymore that that and id start worring.
spookily, I've just been watching fifth gear on 'dave ja vu' and he does indeed say check when engines warm. Nice one Tox. He also said, on average, 8 out of 10 car owners NEVER check there oil. OUCH.
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