At what temp can I use 15w40?

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I recently ordered 3 bottles of Auto-Rx (2 for the engine and 1 for the tranny) to put through a 1997 Subaru Legacy with a 2.2L engine and 170K miles.

Following along in another post, I see that some people recommend starting the cleaning process more gently by using a 15w40 diesel oil, and then using the Auto-Rx. This sounds reasonable to me.

My question is, at what point in the season should I use the 15W-40? I'm located in NE Pennsylvania, and the last date of freezing temperatures (32F) is usually the first or second week in May. Should I wait until it warms up a little before using this oil, or can I get the process started ASAP?
 
It can't get warm enough to use 15w40.
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The viscosity charts list the minimum temperature of 5 degrees f for 15/w40 oil. If you want a 10w/30 heavy duty oil look in the telephone book for oil jobbers .
 
Well, I'll say go ahead and use it now if you so desire ..but keep in mind that there will be 4 or 5 members that will assure you that your engine will spontaniously seize or grenade upon the first turn of the key.

I just put in 20w-50 the day before yesterday to take advantage of the 32F overnight low for a test and it showed very little difference except resultant pressure. Any and all other effects were minor or of very short duration. Your results may vary.

Expect lower fuel economy to varying degrees depending on the lenght of your daily commute. Short commute ...more ..long commute less.
 
Delo 15W-40 is 1750 cSt at 32 degrees F and this compares to most 5W-30 dino's in the 5-10 degree range.

So, while 15W-40 will be fairly thick for 30-40F start-ups in your 2.2L Subaru, it should not pose any problems.

As Gary indicated, it takes 10 to 15 minutes for the oil in the crankcase to reach full operating temperature and the major % of mpg decrease will be during this time interval.
 
quote:

It can't get warm enough to use 15w40.

I suppose that is true in Chicago. In San Diego I use 15w-40 year-round.

Of course if the temperature goes below 50 degrees here it is headline news in the paper on TV.
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My 1994 BMW manual AND SAE certify a 15W down to -20C. My manual then goes on to say that it's acceptable to use this (or any other viscosity listed on the chart) a few degrees above or below they recommended temperature range for "short periods".

Translation (for me): If it starts/cranks, it's probably OK to use...

I've started my car with M-1 15w-50 down to -22C.
 
quote:

Originally posted by San Diego Mac:

quote:

It can't get warm enough to use 15w40.

I suppose that is true in Chicago. In San Diego I use 15w-40 year-round.

Of course if the temperature goes below 50 degrees here it is headline news in the paper on TV.
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Why not run 5w40?
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Because 5-40 is a 'synthetic weight only' and for maximum results, you should use auto-rx with a dino oil.
 
Thanks for the replies. Actually, the advice on the other post was to use the 15w40 before beginning the Auto-Rx process. I was thinking of using the 15w40 to begin the cleaning process more gently.

Then I would drain the 15w40, switch back to my usual dino 5w30, and then begin the Auto-Rx process.

Should I consider using the 15w40 before the Auto-Rx process, or should I just go with the Auto-Rx from the start?
 
quote:

Originally posted by Thorn:
Thanks for the replies. Actually, the advice on the other post was to use the 15w40 before beginning the Auto-Rx process. I was thinking of using the 15w40 to begin the cleaning process more gently.

Then I would drain the 15w40, switch back to my usual dino 5w30, and then begin the Auto-Rx process.

Should I consider using the 15w40 before the Auto-Rx process, or should I just go with the Auto-Rx from the start?


That is what I am doing right now. I just put Delo 400 in preparation for another round of ARX cleaning in my mini-van. Temps are fine ... in fact I plan on using this oil all summer instead of the High Milage oils I was using.

[ April 18, 2005, 08:17 PM: Message edited by: rg144 ]
 
as my engine consumed the 0-30 from before, i topped off nearly 3 litres of 15-40 (redlining quite often) and oil consumption has virtually ceased. It could be the powerful addpack in Castrol RX Super freeing the rings, or its just a stable grade in my engine
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Car still sings at 7300rpm
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quote:

Originally posted by Thorn:
Thanks for the replies. Actually, the advice on the other post was to use the 15w40 before beginning the Auto-Rx process. I was thinking of using the 15w40 to begin the cleaning process more gently.

Then I would drain the 15w40, switch back to my usual dino 5w30, and then begin the Auto-Rx process.

Should I consider using the 15w40 before the Auto-Rx process, or should I just go with the Auto-Rx from the start?


Starting the cleaning process more gently? Thrown the Auto-RX in and stop ***** -footing around about it.
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What grade does your manual state to use for oil?
 
BlazerLT,

You're right. There is way too much information on this site for a fence-sitter like me. I just need to pull the trigger and go with the Auto Rx.

The owner's manual recommends API classification SH or SG. The manual has a temperature chart showing 5w30 being "Preferred" from 40C and below. 10w30 and 10w40 are listed from -20C on up, but it doesn't say "Preferred".

There is another section with recommended grades and viscosity under "severe driving conditions." This list shows API classification SH in SAE viscosity No. 30, 40, 10w50, 20w40 and 20w50.

Wow! I never realized I had so many choices. I'm not a car guy, and I found this site almost by accident. I, and the local iffy lube shops, have been feeding this car a steady diet of dino 5w30 since new.

Do you think it's time for a change? Maybe I should go with 10w30 or 5w40 in the summer, and 5w30 in the winter. I would really like to squeeze another couple of years out of this vehicle, which would put it well over 200K (170+K currently).
 
Hi,
Thorn - to answer your question a quality CI-4/SL mineral HDEO 15w-40 oil can be used between 10f and 100f+

I used a 5w-40 synthetic HDEO in my EJ25 engined Subaru Outback with great success. Subaru engines normally run clean and are not hard on their engine oil whatever it is

Regards
Doug
 
The Delo400 10w-30 would do fine in your temp conditions. If going with synthetic a 5w-40 would do as well.

I really don't see any reason of going 15w-40 with the Subaru you have given your climate.
 
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