Will a oW-XX hurt my engine?

[y_p_w]

quote:

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Originally posted by goodvibes:
You would still be wasting more energy keeping the oil warm when not in use than you would gain in mileage but I'm sure it's good for the motor. The VI improvers are not as prevalent in synths since they have a large natural viscosity index without improvers. 10w30s need virtually none and a 0w30 doesn't need that much if it starts as a thin 30w. The improvers work well and pretty linearly but wear out over time. It still won't make the same brand of a used synth 10w30 thinner than a 0w30 at cold temps unless they are at different ends of the 30w scale. How a possible answer to the question of 0Ws being bad got to 'it might be to thick' at colder temps is beyond me.

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My understanding about VI improvers is that they're molecules that tend to expand with temperature. I would suppose that there's an upper limit at which they no longer expand and a lower limit where they no longer contract. Suppose two different types of VII with different expansion characteristics are used. It'll probably be fairly linear, but there seem to be some non-linear effects in some of the blending experimentation I've seen in the VOA section.

My comment about 0W-30 is that there seems to be an assumption that any 0W-30 has to be thinner than a 5W-30 at ambient temps, which isn't true. "German Castrol" 0W-30 is thicker (68.5 cSt) than Mobil 1 5W-30 (64.8 cSt) at 40°C.

As for the thing about warming up the block with a heater, I wasn't suggesting that it be left on all the time. A simple timer would suffice. A 400 W heater left on for 30 minutes probably isn't that much compared to the additional fuel at today's prices. I wouldn't do it myself, since I might forget to unplug the thing before exiting my garage.

 

[goodvibes]

Your basically citing my earlier example of M1 and the green. The Castrol is thicker at 40*c(already warmed up at 104* F) and above because it is a thicker oil to begin with and the visc. curves have already crossed. Raise the temp a bit and it will be thicker than the 10w as well. Again, what does a couple of points one way or the other during warm up have anything to due with breaking his motor especially when the 0w IS flowing better when COLD. These things just don't matter in the summer and at 40c you sure don't need a block heater or to worry about mileage.

[ May 11, 2005, 11:42 PM: Message edited by: goodvibes ]

 

[y_p_w]

quote:

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Originally posted by goodvibes:
Your basically citing my earlier example of M1 and the green. The Castrol is thicker at 40*c(already warmed up at 104* F) and above because it is a thicker oil to begin with and the visc. curves have already crossed. Raise the temp a bit and it will be thicker than the 10w as well. Again, what does a couple of points one way or the other during warm up have anything to due with breaking his motor especially when the 0w IS flowing better when COLD. These things just don't matter in the summer and at 40c you sure don't need a block heater or to worry about mileage.

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I used to think a 0W-30 would be the magic elixer for better cold starts (and lower wear) at ambient temps where I live. There's someone here who's sig says something about no oil is thin enough at startup. Now I don't personally think it's that big a deal. However - the 0W means one thing and the 30 means another. What happens inbetween isn't necessarily defined by the endpoints.

 

[n8wvi]

For some reason (the post didn't say why, and I can't remember where I saw it, noria maybe?), Subaru in Europe is SPECIFICALLY RECOMMENDING AGAINST 0w-xx until they do further testing.
Could it be that they think the oil may be too thin during warmup? I know it's fine at operating temp, and that a cold 0W is thicker than a hot 40, but during warmup, the clearances are different, and no one can argue against the fact that a cold 0W is thinner than a cold 5W.

Dave

 

[MGBV8]

Subaru - This information has been received from Mobil.

Mobil 1 0W-40
Subaru Japan have stated that all oils with a 0W rating will invalidate engine warranty. This is because 0W viscosity has not been tested by Fuji Heavy Industries and is unlikely to be tested by them in the near future. It is not a result of engine problems and is not related to synthetic technology or oil quality.

This is a few years old now.

 

[tharoka]

Any links available for this last info?

 

[Bryanccfshr]

quote:

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Originally posted by n8wvi:
no one can argue against the fact that a cold 0W is thinner than a cold 5W.

Dave

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What is cold? Unless we are talking about instant frostbite temperatures the 0w oils are often thicker at ambient temps than 5 and 10w oils of the same line, read around. this has been discussed for a couple of days.

 

[SilverGGA@Work]

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Originally posted by MGBV8:

This is a few years old now.

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Yup, that's really old info when those UK Suby guys wondered whether they could use 0w-40.

 

[y_p_w]

quote:

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Originally posted by tharoka:
Any links available for this last info?

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A letter received from Mobil's UK division:

http://forums.nasioc.com/forums/archive/index.php/t-36697.html

quote:

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The product recommended for new Imprezas is Mobil 1 5W-40 which we supply to Subaru dealerships. Unfortunately it is not available through any other retail channels.

Mobil 1 0W-40 is not approved by Subaru for new vehicles. Mobil 1 Motorsport could be used for older cars that are out of warranty.

With regard to using a fully synthetic engine oil in a new vehicle, we would have to say it depends. The trend now is for new vehicles to go to the normal service interval before an oil change is done. Therefore, full specification products are used from the word go. This means that the 'running in' period has effectively gone and owners should follow the advice given in the owner's manual on how to operate the vehicle from new.

Our information is that Subaru recommend an oil change interval of 7500 miles or 6 months, which ever comes sooner, for their turbo charged 2 litre
models from 1991 onwards. If you are going to use Mobil 1 5W-40 it would seem sensible to fit when it goes in for the first service.

If your dealer is not supplied by Mobil you could ask our Customer Service dept if they can identify a dealership where we do. They can be contacted on
0800 243413.

Fred Wells
for
Barbara Hurley
Technical Help Desk
Mobil Oil Co. Ltd.
Great Britain
[email protected]

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[Audi Junkie]

quote:

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too thin during warmup?

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[y_p_w]

quote:

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Originally posted by Audi Junkie:

quote:

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too thin during warmup?

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Sure. Ever heard of smoke on startup or leaking past seals when cold? I thought seals swell a bit, and of course metals expand with increasing temps. Some people go to 15W-40 or 20W-50 as a crutch.

However - I don't think it should be a problem if everything is mechanically sound.

 

[goodvibes]

I'm sure some of that oil gets past the seals while it's warm and thin after turn off.

[ May 13, 2005, 06:43 AM: Message edited by: goodvibes ]