[ds968]

I have been using Amsoil's 5w-40 pretty much year-round ( daytime temps here rarely get below 60s and rarely above 80s ), and once in a while in the so-called summer I mix in just one quart of their 10w-40 with the rest staying at 5w-40..

But I see all these different numbers available and really have no clue how the two numbers relate to one another, and for that matter how do you tell which one is "heavier". I expect 10-40 is heavier than 5-40, but then how/where does 15-50, or 20-50, or 0-40, etc ..fit in to the scheme of things ? <img src="/forum/images/smilies/968/huh.gif" class="smilie" alt="" />

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[banditsc]

I use Amsoil's 10w40 premium as it's the one with the added ZDDP, their European 5w40 doesn't state it has the added ZDDP for our cars.

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[flash]

5 is pretty light for where you live



I would keep the expansion differential as low as possible



The higher the second number, the higher the temp to which it will work before it breaks down



I would run 10-40 where you live, since it does not get so cold as to create a starting problem

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[pure&amp;simple]

Pete recommended Redline 15/50 to me, and that is what I have always used. I don't drive the car in the winter, though.

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[flash]

yeah - you track yours, so the higher temp protection is a needed thing, as your oil temps would regularly get to 260

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[ds968]

thanks, switching to 10-40 at next change . btw, what about the theory that lighter oil = faster revs / more power.. myth ?

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[Cloud9...68]

"thanks, switching to 10-40 at next change . btw, what about the theory that lighter oil = faster revs / more power.. myth ? "



I believe there is data backing this up, but it comes at the expense of longevity.

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[flash]

not a myth - but, you have to keep in mind the high number of the two, as that is what it pumps up to when it's warm - so, no real difference between 5-40 and 10-40 when they are clean - the 5-40 will have less resistance, as it will break down faster than the 10-40, and not expand to 40 when it is dirty - the difference is going to be very small though

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[ds968]

I can't remember at the moment on which thread we were recently talking about oil pressure, but I do remember saying that at idle with the car fully warmed up, the indicator was right in the middle between 2 and 3.. tested that yesterday, after running the car for about 30 min .. and it's only a bit above the 2 line, but not quite in the middle b/w 2 and 3. In any gear, it's still always right at the bottom edge of the 5 line. This is with 5-40. I'll see if the bar moves from that 2.2-ish mark when I put 10-40 in the car..

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[gcb729]

I'm in AZ and heat is a reality pretty much all year. I've been using Mobil 1 15W50 and it seems to be just fine. Porsche certifies Mobil 1 0W40 for Porsche cars newer than 85 1/2. The desired grade I use is increasingly hard to find, now that most modern vehicles are using 5W30, 5W20, etc. For the most part picking the lower startup flow weight of the oil is primary for your geographic location and for most Porsche owners who tend to drive in the "SPIRITED" category should deliver the highest weight of oil to their cars as possible. I'm not sure if a 0W50 exists commercially, but that would be my choice world wide. I believe a 5W50 exists, I'm heading towards that.

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[Trueblue]

I haven't had had the 968 long, but it seems to like the Mobil 1 15W/50 I feed it. I Thought about saving the $$$ and using a non synthetic due to the high oil consumtion of the motor, which I understand is typical.



<img src="/forum/images/smilies/968/biggrin.gif" class="smilie" alt="" />

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[Monstrous4Banger]

[quote name='gcb729' timestamp='1310926239' post='112729']

I'm in AZ and heat is a reality pretty much all year. I've been using Mobil 1 15W50 and it seems to be just fine. Porsche certifies Mobil 1 0W40 for Porsche cars newer than 85 1/2. The desired grade I use is increasingly hard to find, now that most modern vehicles are using 5W30, 5W20, etc. For the most part picking the lower startup flow weight of the oil is primary for your geographic location and for most Porsche owners who tend to drive in the "SPIRITED" category should deliver the highest weight of oil to their cars as possible. I'm not sure if a 0W50 exists commercially, but that would be my choice world wide. I believe a 5W50 exists, I'm heading towards that.

[/quote]



FWIW, I run 20-50 amsoil in the desert. Always have in my 944/68's. 10 years now. I wouldnt run anything else personally. If you need a source for a local amsoil dealer let me know.

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[Trueblue]

I was involved with some motor oils testing many years ago, and we found the Amsoil tended to be prone to foaming more than the Mobil 1 and a few other synthetics. Maybe they reformulated it since then, we shared our findings with them...

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[ds968]

My mechanic seems to think very highly of TOTAL . He used Mobil 1 ( he really likes Amsoil as well but claims it's a bit of a PITA to get it as easily and with as much of a discount as Mobil..) for all of the Porsches and BMWs and MBZs he has worked on for 30 years+ as well as for his own cars and his brother's Ferrari, but now just switched to TOTAL as the standard, unless of course customers request another brand due to price, or brand loyalty, etc. I checked around and it's a bit costly at $ 11 / quart, but hey if it's good enough for Formula 1, it's good enough for anyone else, right ? <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" /> I'm staying with Amsoil for a while, at least until TOTAL has had a long run in the U.S. and there is enough empirical data that supports the claim that it may indeed be the top choice

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[Cloud9...68]

Oil is one of those highly subjective topics, for which it's difficult to get reliable, unbiased data. For a couple more data points, Terry Dyson of Dyson oil analysis (he's been doing it for over 30 years) recommends something called Bio-syn, but also likes Shell Rotella, which is actually designed for diesels, and Mike Lindsay of Lindsey racing absolutely swears by Joe Gibbs oils. It's enough to make your head spin...

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[gcb729]

Using Total by a commercial shop as I'm finding out has a lot to do with who WorldPac (the leader in next day delivered Import Car Parts) is getting the best deal from. I have access to the inside of Import Parts Business - Total is huge with them. I at least use a Porsche recognized certified motor oil, but most are good and have slightly different formulation - what that formulation is well it's protected and proprietary.

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[RS Barn]

I get my Red Line from WorldPac as well. Premium oils have a high price and to pay shipping on top is brutal.

The oils I've had luck and experience are RED LINE, and Joe Gibbs. Not a fan of Mobile 1 for several reasons.

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[gcb729]

I have been lead to understand that European Spec Synthetic and USA spec Synthetic oils may be different. Since synthetic oil just use a more refined base stock or more accurate to say a higher percentage of this refined base stock than is used to define the difference between Synthetic and "natural" oil is a very fine line. I understand the USA Mobil is not as high quality as what is available in Europe. I wish I could define this, but my home "LAB" equipment is very, very limited - as in - I have a decent tool box to fix my Porsches. I'm currently running some LubroMoly, nothing exotic, but seemingly good quality.

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[Mark]

I usually get my Redline from Amazon due to the free shipping but have gotten from places like SummitRacing when I could get a deal and free shipping.

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