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- - Oil Change, Royal Purple (http://986forum.com/forums/showthread.php?t=7795)

Quote:

Originally Posted by MNBoxster

Hi,

Sorry, but I don't agree.

The shear stress of a petroleum oil or other Newtonian fluid at a given temperature varies directly with shear rate (velocity). The ratio between shear stress and shear rate is constant; this ratio is termed viscosity. The higher the viscosity of a Newtonian fluid, the greater the shear stress as a function of rate of shear.

In a non-Newtonian fluid -- such as a grease or a polymer-containing oil (e.g., multi-grade oil) -- shear stress is not proportional to the rate of shear. A non-Newtonian fluid may be said to have an apparent viscosity, a viscosity that holds only for the shear rate (and temperature) at which the viscosity is determined. The shear failure point in most oils is between 4,000 and 8,000 psi. Source - http://www.lemd.com/motorsport/previous.cfm?id=19

Newtonian fluid - a fluid with a constant viscosity at a given temperature regardless of the rate of shear. Single-grade oils are Newtonian fluids. Multigrade oils are NON-Newtonian fluids because viscosity varies with shear rate. Source - http://www.oilanalysis.com/dictionary/default.asp?definitionsearch=xqxqxqxq222&alphasear ch=N

Newtonian Flow - Occurs in a liquid system where the rate of shear is directly proportional to the shearing force, as with straight grade oils which do not contain a polymeric viscosity modifier. When rate of shear is not directly proportional to the shearing force, flow is non-Newtonian, as it is with oils containing viscosity modifiers. Source - http://www.chevron.com/products/prodserv/ehl/techterms.htm

I rest my case... ;)

Happy Motoring!... Jim'99

I'm not trying to argue that a multi-viscosity non-synthetic motor oil is or isn't Newtonian, honestly, I don't know.

Your comment above suggested that the fact that the oil changes viscosity with temperature makes it non-Newtonian. This isn't what would make the oil non-Newtonian, it would be the fact that the fluid shear forces are not linear with the strain on the material.

Quote:

Originally Posted by blue2000s

Hi,

Fair enough - PEACE!... :cheers:

Happy Motoring!... Jim'99

Quote:

Originally Posted by pecivil

no, 0-40 is not for cold climates. I would never use 15-50. It is much too thick, no matter where you are, or how hot is it outside.

read the articles in the link I gave below. Again, it is long, but if you can follow it, you will understand why 0-40 or even 0-30 is the better oil to use.

15-50 is needlessly increasing the amount of time that it takes the oil to reach operating temp at startup. This results in an increased time to achieve proper lubrication, and an increased time of extreme engine wear. All oils achieve the proper viscosity at operating temps.

The real variable is how long it takes the oil to get to proper temperature (i.e. to thin out) AT STARTUP.

the thicker the oil, the much, much longer it takes.

Anyway, on my boxster, there is a sticker on the trunk lid near the oil filler neck that clearly states "Use Mobil 1 0-40 ONLY"

Actually before 0-40 M1 was available, M1 15W-50 was routinely recommended for our cars. Many older Boxster manuals still have this weight listed for our cars, depending on outside temp.

15W50 is also commonly used for tracking the car.

You should also know that M1 0w-40 does tend to shear down to a 30 wt oil pretty quickly.

So, depending on where and how you are driving, 15W-50 IS an approved oil for the Boxster.

Having said that, I would use Red Line 5W-40 on the track without hesitation, the only such oil I can say that about.

RP is a good PAO based Group 4 synthetic. No magic, just a very very good oil.

"Also, Porsche specifically recommends Mobil1, not merely a synthetic. This is not due to broad availability or some SweetHeart deal they have with Mobil Oil. Mobil1 is truly the best of all the synthetics. It is produced using the PAO method (meaning it is a true synthetic with no trace amounts of Sulphur or Phosphorus which Dino Oils contain, and which are very destructive to an engine). And, Mobil1 contains only 10%-12% addditives by volume (depending upon the type). Royal Purple and RedLine contain nearly twice as many additives by volume meaning that they actually contain less Base Stock Oil/volume, in other words, there's more Oil in Mobil1 than RedLine or Royal Purple. They're not necessarily awful, but they're not as good as Mobil1."

We are going to disagree on this one Jim. Most oil experts I know would take an Ester based oil over an PAO oil any day of the week. However, they are more costly on balance.

I have seen used engine oil analysis done on Red Line vs M1. The RL oil simply does better on these tests, hands down.

This does not mean that M1 does poorly, in fact it is a superior oil. However, it DOES tend to shear quickly in HP engines like the Box. The ester based RL oil does particularly well in shear tests, and has the highest HTST rating of any oil I have ever seen. That is why racers love RL.

Moreover, the wear levels of RL in used oil analysis are superior to any oil I have seen tested.

I am not arguing against M1, I use it in my BMW. I use RL in my air cooled M/C, as it handles the heat much better than M1.

BTW- Overall, PAO oils test out to be a bit inferior to Ester based synthetics, but then again, they usually cost less.

Lastly, the 15W-50 oil is fine to use depending on temp and use. It used to be in the manual but that stopped when the M1 deal got cut with Porsche.

I forgot to mention (maybe for the benefit for some of the Chicago area Boxster owners) I was only charged $66.00 for the oil & filter change from Motor Werks (Barrington) since I supplied my own oil (Red Line 5W40). I thought this was a very fair price.

Quote:

Originally Posted by bmussatti

Thanks, bmus !

Where did you pick up the Red Line ? Locally or online ?

Does MW still charge $110 if they supply the oil ?

Did they do it while you waited ? How long did it take ?

Nick

Quote:

Originally Posted by NickCats

Thanks, bmus !

Where did you pick up the Red Line ? Locally or online ?

Does MW still charge $110 if they supply the oil ?

Did they do it while you waited ? How long did it take ?

Nick

Hey Nick:

1) I bought the Red Line locally. Do an e-Bay search. The place is in the Schaumburg area. I went and picked it up for $76 complete with sales tax for 10 quarts. The place is called Roadmaster Transmissions.

2) Yes, MW still charges $110 for Mobil 1 oil change

3) I waited. Takes about 1 hour. Call Brian and make an appointment 847-381-8900. They do Saturdays too.

Quote:

Originally Posted by NickCats

Thanks, bmus !

Where did you pick up the Red Line ? Locally or online ?

Does MW still charge $110 if they supply the oil ?

Did they do it while you waited ? How long did it take ?

Nick

Nick, use this link for the phone number, they have all of the Red Line products:

http://cgi.ebay.com/ebaymotors/5W30-Red-Line-Synthetic-Engine-Oil_W0QQcmdZViewItemQQcategoryZ46098QQihZ013QQitem Z230037310747QQrdZ1QQsspagenameZWDVW

Quote:

Originally Posted by Brucelee

Lastly, the 15W-50 oil is fine to use depending on temp and use. It used to be in the manual but that stopped when the M1 deal got cut with Porsche.

Thanks Bruce, thats reassuring...I would hate to think i spend 59.25 on 9 quarts of oil that isnt good for my boxster...So far the car is better than ever when it comes to acceleration, this morning it felt alot better than it usually does in the AM.