choice of engine oil

[Fraser79]

Hi all, would like to know what kind of oil do u guys uses for a bone stock bpt? Would 15w-50 too thick for the task??

[TheMAN]

15W50 definitely too thick
go with 5W40 or 0W40 synthetic

[Fraser79]

wouldn't that be too thin? weight seems to be those for na

[TheMAN]

no it isn't
it offers more than adequate protection and lubrication to your engine

the oil isn't thin enough to get washed down by petrol or sheared down, but it is thin enough to reduce pumping losses, oil temperatures, and ensure flowability

the lighter cold weights also reduces startup wear... you want as thin as possible for startup since thick oil means it doesn't flow well

[Clean_Cookie]

read the article davoaust posted up from a ferarri forum on oils, its a great read with lots of indepth explaination. in the theoretical world, even 0-60W is too thin. But you need to choose the thinnest oil that your engine can run without burning excessive amounts. (id personally recommend 5 to 10-40 etc.

[derb]

0 is definitely too thin unless you're living in Tassie or up in the mountains. I run 10W40 Royal Purple since I've had my car with a BPT, no issues, still going strong after 160000km.

[TheMAN]

no it isn't
the 0W is the viscosity at AMBIENT temperatures
once warmed up, a 0W40 oil is no different than 10W40

you want the thinnest possible for cold starts to REDUCE wear and have oil quickly flowing

[derb]

I really don't think it's necessary here in Australia to run 0w. Especially on old engines that probably need a slightly thicker oil due to normal wear and tear on rings, etc. I'm no expert, but by choice I will never run a 0W in my motor. In a brand new motor, sure. In one with 150000+ kms, no thank you.

[TheMAN]

had you poured 10W40 oil out of the bottle on a hot summer day? It's still pretty thick
if you poured the 0W40 oil out, it comes out easier... that's the difference in flowability

a cold started engine even on a hot day will have high oil pressures no matter what... and high pressures means low flowability.... oil pressure is inversely related to flow... too much no flow, too little no flow... 0W oils strikes a good balance and allows the oil to quickly flow to the valvetrain while the engine is cold.... this lets you able to quickly drive off without having to sit around to let the engine warm up, which wastes petrol

you can NEVER have oil that's too thin for cold starts, this only applies to hot engines
you don't "need" it in Australia, and neither do you in Arizona... but the same concept applies

the benefit of this thin oil extends to allowing the HLA lifters to quickly get oil and reduce the lifter tapping noises

there should be NO oil consumption increase if your engine is mechanically sound, even with more than 150000km.... well formulated 0W40 oils have high shear stability rates, higher flash points, less volatility, and have loads of antiwear additives... the only way to find out is to try it since each motor is different... and even if it did burn oil, there's no harm to it... just simply switch back to whatever you were using before and go on with life!

go on fearing it and you will never know the benefits of these recently engineered 0 weight oils... motor oils have come a long way in the past 10 years mate... I read and learned a lot in recent years and I come to find saying/doing things that I would never had dreamed of 10 years ago! It's best to keep an open mind since oil technology changes for the better much like anything else in this world...
people always think "oil is oil" but there is much there is to know than just marketing and product labels! Not one oil is the same... brand, specific line up, specific grade, etc... in its robustness and choice of materials to make it

[DavoAust]

The link ryan refered to is this one:
http://www.ferrarichat.com/forum/sho...d.php?t=136052
Its basically the holy grail when it comes to choosing oil.

How many km on the engine? Does it blow smoke at startup? High revs? After compression braking?

If its using a little oil, 10W-40. Almost none, go 5W-40. Look at dropping down to a xW-30 in the future. I'm deciding on my current change in the 3000, looks like I'll be going either 5W-30 or 0W-30.

Be aware that I'm recommending based on synthetics (that link discusses the advantages). I can't see any sane reason not to run synth other than during break in of a new engine/build. They last longer, work better and clean a lot of the gunk out of the engine. If the BPT has been running mineral oil till now, recommend dropping the synth at around 3000km after the change. It will be black from all the old deposits its cleaned out.

[Mad Mat]

id go with the 10w-50 by penrite... thats what i have always used and its just as good as royal purple and half the $$$$

[Clean_Cookie]

penrite has just released that new fully synthetic range, which is what you would want to buy... davo, who would you want to use a x-30W? the second number protects the engine at high temps, its not that it gets thicker, its just that it thins less... providing more protection at higher temps (as a 30 might be the same thin-ness at 100*c as a 70 at 150*C...), and i have no idea about temps etc but thats how it was explained to me. if youre thrashing your engine and it gets hot, then once it gets too hot, the oil will provide less protection.

[project.r.racing]

the 1st number is the weight of the oil at room temp. the second number he how well it keeps that original weight at higher temps.

so a 0w40 and a 10w40 are not the same at higher temps as previously posted.

15w40 vs 15w60, both are the same thickness at room temp. but one will thin out at say 45C and the other will thin out at 65C.

when an oil starts to thin out, then it fails to protect the engine correctly, as the pump may not get correct pressures etc.

[derb]

Originally Posted by project.r.racing

0w40 and 10w40 are not the same at high temps.

That's what I thought. Even my owners manual tells me not to use 0W unless my normal ambient temp is below 15 degrees C. For my temp range in here in Queensland it says to use a 10W oil.

[mynameisdaniel]

Originally Posted by project.r.racing

the 1st number is the weight of the oil at room temp. the second number he how well it keeps that original weight at higher temps.

so a 0w40 and a 10w40 are not the same at higher temps as previously posted.

15w40 vs 15w60, both are the same thickness at room temp. but one will thin out at say 45C and the other will thin out at 65C.

when an oil starts to thin out, then it fails to protect the engine correctly, as the pump may not get correct pressures etc.

At high temperatures they won't be the same, but at operating temperatures (100C) they will be the same viscosity.

If you service your car regularly the oil thinning will never be a problem.
The difference between the first number is how thick the oil gets when it's cooled down. You want it as thin as possible at startup so it flows better and lubricates better, making 0W-40 better than 10W-40.
The problem being that if you run the oil too long the additives wear out and you end up running straight 0W or straight 10W which are both too thin at operating temperature but 10W is slightly closer to what it should be.

This only really applies to non synthetic oils and is my understanding of how oils work after a bit of reading.

[Clean_Cookie]

its also heavily influenced by the origin of the synthetic oil....

[TheMAN]

Originally Posted by project.r.racing

the 1st number is the weight of the oil at room temp. the second number he how well it keeps that original weight at higher temps.

so a 0w40 and a 10w40 are not the same at higher temps as previously posted.

15w40 vs 15w60, both are the same thickness at room temp. but one will thin out at say 45C and the other will thin out at 65C.

when an oil starts to thin out, then it fails to protect the engine correctly, as the pump may not get correct pressures etc.

is that so?
then why does Redline's 0W40 has 15.1 centistokes at 100 degrees while their 10W40 has 14.6 centistokes at 100 degrees?
http://www.redlineoil.com/content/fi...uct%20Data.pdf

the higher the number, the thicker it is!

the "0 weight" oils usually have high viscosity indexes which makes for a very stable oils due to less or no viscosity improvers involved, which removes any concerns of the oil becoming a 10W or 0W oil after too many miles... in fact, what everyone should be concerned about instead is how well the oil withstands high temperatures and high shear stresses... good synthetic oils can withstand that... the HTHS centipoise number indicates this fact in oil specs... the higher the better


oh and google is your friend
http://themotoroilevaluator.com/memb...iscosity-oils/
http://www.upmpg.com/tech_articles/motoroil_viscosity/

[TheMAN]

Originally Posted by derb

That's what I thought. Even my owners manual tells me not to use 0W unless my normal ambient temp is below 15 degrees C. For my temp range in here in Queensland it says to use a 10W oil.

you realise your owner's manual was published 20 years ago based on oil data/technology that's at least 5 years older than that right? Mazda never publishes their manuals based on the latest specs because they know availability is not always immediate

as I said before... oil technology evolves, just like anything else out there... no one would've dreamed 10 to 20 years ago that brand new cars from most major auto makers will be using 0W20 synthetic oil (for non-turbo engines), which works fine in a wide range of temperatures, including the ones in Australia

what is said in the manual is a mere guideline... if you're smart about it, you can wisely choose an oil that exceeds all requirements mazda specifies and you'll end up with an engine that not only lasts longer, but reduces friction

[DavoAust]

Originally Posted by project.r.racing

the 1st number is the weight of the oil at room temp. the second number he how well it keeps that original weight at higher temps.

so a 0w40 and a 10w40 are not the same at higher temps as previously posted.

15w40 vs 15w60, both are the same thickness at room temp. but one will thin out at say 45C and the other will thin out at 65C.

I think you should go learn about oils. You are so far off the mark its not even joke worthy. Go read that link I posted.

A 10w-30 and a 0w-30 are identical at running temperature. They differ at cold start time where the 0 weight is thinner (and better, its closer to operating vicosity) than the 10 weight oil. Its not a measure of how 'how well it keeps that original weight at higher temps', its the exact opposite. Its a measure of how much the oil thickens when cold.

Derb: edwin is spot on. Oil technology has changed so much since the 80's and 90's. Synthetic oils have made old techniques and recommendations completely incorrect. You need to look at what your operating conditions are and use the oil that suits. You track the BG so a 10W-40 is probably the correct choice

[TheMAN]

on the contrary dave, the 5W40 was the clear winner for me over the 10W40 Redline because the vicosity index was better, thicker viscosity at 100 degrees, higher flash point, and most importantly... more detergents and antiwear additives... a requirement to meet the API CJ-4/CI-4 diesel oil rating

5W40 oils will almost always use better base stocks than the 10W40 oils... with this, you stand to benefit to use it over the 10W40

the bottom line is... educate yourself with the basics of oil terminologies first, then go read actual datasheets and oil analyses from users to make an EDUCATED choice... nothing is worse than just blindly choosing by faith or brand loyalty