Engine Oil Viscosity
20 October 2013, 03:54 PM
#33
Very good explanation Tim. 
I think there have been some misconceptions that multi grade oils such as 10w-40, 15w-50 actually become thinner during winter and thicker at 100 deg cel.
"ALL oils are THICKER at low temperatures than at high temperatures but the lower the “w” number, the quicker the oil will flow at low temperatures."
I basically alternate between these 2 oils:
Motul 300V 10W-40 and 300v 15W-50.
I mainly use the 40 for everyday use. but switch to the 50 when i track the car or will be using it harder than usual.
Now with the car getting on in age (over 60k miles now), the consumption rate for the 40 is approximately half to 3/4 quarts every 4k miles. Which i think is totally acceptable?
Should i really be using the 50 from now on? There is almost no consumption with the 50. The only reason i don't like using the 50 is because the car does feel less responsive - which is to be expected.
Should i go for 40 or would my engine thank me for using 50 even for daily use?
It's for a choco pistoned EJ257 08 STI by the way.
I think there have been some misconceptions that multi grade oils such as 10w-40, 15w-50 actually become thinner during winter and thicker at 100 deg cel.
"ALL oils are THICKER at low temperatures than at high temperatures but the lower the “w” number, the quicker the oil will flow at low temperatures."
I basically alternate between these 2 oils:
Motul 300V 10W-40 and 300v 15W-50.
I mainly use the 40 for everyday use. but switch to the 50 when i track the car or will be using it harder than usual.
Now with the car getting on in age (over 60k miles now), the consumption rate for the 40 is approximately half to 3/4 quarts every 4k miles. Which i think is totally acceptable?
Should i really be using the 50 from now on? There is almost no consumption with the 50. The only reason i don't like using the 50 is because the car does feel less responsive - which is to be expected.
Should i go for 40 or would my engine thank me for using 50 even for daily use?
It's for a choco pistoned EJ257 08 STI by the way.
If you don't mind swapping oils for hard use or the bit of consumption with the 10w-40, then what you are doing is ideal. If you'd rather just use one oil, go for a quality 10w-50.
Cheers
Tim
20 October 2013, 03:59 PM
#34
dont know mate, was told although it says that in the manual, its not actually the recommended oil, its the lowest you can get away with. Apparantley the 5w is too thin for the barings and causes them to fail prematurely.
I checked with a few different tuners (some very respected) and they all said the same thing.
I use 10w60, but I do drive my car very hard.
I checked with a few different tuners (some very respected) and they all said the same thing.
I use 10w60, but I do drive my car very hard.
20 October 2013, 04:03 PM
#36
I'm about to change mine to 15-50 and i'm just coming up to 100k was using 10-40 but did a bit of reading and it seem higher milage cars are better run on 15w mine is garaged at night and the temps here just about make it to zero overnight for a couple of months.
No smoke and uses less than 1/4 litre every 1000/1500 miles dependant on use, lot's of short 10/15 mile journeys so I think that has something to do with it.
No smoke and uses less than 1/4 litre every 1000/1500 miles dependant on use, lot's of short 10/15 mile journeys so I think that has something to do with it.
20 October 2013, 04:08 PM
#37
So I just sell oil and know nothing about it? If that's what you think, go with what your tuner thinks.
Yes, we do repeat technical threads on other sites, but nothing mentioned above is Subaru specific, it's just general information about oil viscosity.
20 October 2013, 04:10 PM
#39
My 380bhp STi hawkeye runs on millers 10w 40 with 55k miles on the clock, have never noticed that it uses/burns any oil. Due a oil change in the next few weeks and going to try 10w 50!!!
Been told by a number of Subaru owners and Subaru garages not to run 5w oil as its to thin , was also talking to a someone the otherday who had a customer come in with bad engine slap on a 2.5 which was using 5w oil and advised them to change to a 10w oil and the slap went away!!!!
Been told by a number of Subaru owners and Subaru garages not to run 5w oil as its to thin , was also talking to a someone the otherday who had a customer come in with bad engine slap on a 2.5 which was using 5w oil and advised them to change to a 10w oil and the slap went away!!!!
20 October 2013, 04:14 PM
#40
http://www.opieoils.co.uk/c-656-5w-40.aspx
Cheers
Tim
20 October 2013, 04:31 PM
#42
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I have just checked the handbook, it says the 5w30 is recommended for fuel economy only, on the next page, it goes on about driving the car under severe conditions, and it does say to use a thicker oil.
21 October 2013, 09:19 AM
#46
I wasnt attacking you or your business, but some of the people I have spoken to regularly build engines, and record breaking cars. I cant see how they would be wrong, when they push these cars far beyond anybody else.
I have just checked the handbook, it says the 5w30 is recommended for fuel economy only, on the next page, it goes on about driving the car under severe conditions, and it does say to use a thicker oil.
I have just checked the handbook, it says the 5w30 is recommended for fuel economy only, on the next page, it goes on about driving the car under severe conditions, and it does say to use a thicker oil.
There was a tuner on here that recommended using a 15w-40 mineral oil and when we kept pushing him for an answer of why as he kept telling us we were wrong for suggesting something else, he eventually admitted it was because his staff would nick anything better than that, so why people recommend something is not always as simple as what is best for the car. I wish I bookmarked that thread.
Yes, going thicker than a 5w-30 is fine if the car is getting harder than standard use, but there is a big difference between a bit thicker and something like a 15w-50 or 10w-60, which is so two or three times as thick. A 5w-40 is a bit thicker than a 5w-30, a 10w-60 is for a different engine.
Cheers
Tim
21 October 2013, 09:20 AM
#47
Hi Gary
I'd go for a 10w-50
http://www.opieoils.co.uk/c-659-10w-50.aspx
The Nanodrive CFS is, on paper, the best oil available, but the Pro S and CFS are both really good oils, so all are good choices for your car.
Cheers
Tim
21 October 2013, 09:32 AM
#48
It's not something we deal with so I don't know much about it. According to the information I've just seen, it's not ester based and looking at the price of it, I very much doubt it would be a PAO either, so most likely to be a hydrocracked mineral oil, something that I generally would not consider a race quality oil, although it's a viscosity that tends to be used in modified or race engines.
Cheers
Tim
My first thought was that you were trying a wind-up
22 October 2013, 09:45 PM
#52
What about semi synth vs fully synth?
You can't seem to get 10W 40 fully synth. So would I be better to use 5W 40 fully synth or 10W 40 semi synth in my 2007 Hawk STi?
Car has 33K miles on it has filter, decat exhaust, fuel pump and remap to 350. Not showing any signs of too much burn off.
Usage is frequent short runs w th as much abuse as possible given the chance
You can't seem to get 10W 40 fully synth. So would I be better to use 5W 40 fully synth or 10W 40 semi synth in my 2007 Hawk STi?
Car has 33K miles on it has filter, decat exhaust, fuel pump and remap to 350. Not showing any signs of too much burn off.
Usage is frequent short runs w th as much abuse as possible given the chance
22 October 2013, 10:00 PM
#53
What about semi synth vs fully synth?
You can't seem to get 10W 40 fully synth. So would I be better to use 5W 40 fully synth or 10W 40 semi synth in my 2007 Hawk STi?
Car has 33K miles on it has filter, decat exhaust, fuel pump and remap to 350. Not showing any signs of too much burn off.
Usage is frequent short runs w th as much abuse as possible given the chance
You can't seem to get 10W 40 fully synth. So would I be better to use 5W 40 fully synth or 10W 40 semi synth in my 2007 Hawk STi?
Car has 33K miles on it has filter, decat exhaust, fuel pump and remap to 350. Not showing any signs of too much burn off.
Usage is frequent short runs w th as much abuse as possible given the chance
http://www.ebay.co.uk/itm/Gulf-Compe...d=534748171187
And got myself a bluprint oil filter!!!
http://www.ebay.co.uk/itm/2302690654...d=534748674033
So hoping the weather holds off the weekend so I can do a oil change!!!
22 October 2013, 10:37 PM
#54
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Ive just ordered for my 06 STi hawk the 10w 40 Gulf competition oil which is ester based, which reading up on millions of threads on oil, is a good thing!!
http://www.ebay.co.uk/itm/Gulf-Compe...d=534748171187
And got myself a bluprint oil filter!!!
http://www.ebay.co.uk/itm/2302690654...d=534748674033
So hoping the weather holds off the weekend so I can do a oil change!!!
23 October 2013, 12:03 AM
#59
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http://www.ebay.co.uk/itm/Subaru-Imp...item4177b00bb6
oil filter for £38
23 October 2013, 07:08 AM
#60
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buy this i dare you, she'll kick you out for real
http://www.ebay.co.uk/itm/Subaru-Imp...item4177b00bb6
oil filter for £38