[sasilverbullet]

Had been running Mobil 1 15w-50 here in hot south texas.



Changed the oil last week to amsoil euro blend 5w-40 pure syn, ever since then two nagging things have disapeared:



1. When starting the car before, when it fired up, it would dye right away. Restart worked fine.



2. When cold, running A/C, push clutch in, engine would dip VERY low rpm wise and sometimes die.



Since the oil change to the lower weight oil, both have gone away completely AND the car seems to rev much quicker!



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



Cool!

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[Renalicious]

Doh! And I just bought 2 containers of Mobil 1 15-50 too. I'll comment if I see any problems when I start using it.

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[Cloud9...68]

Not to dampen your enthusiasm, but aren't you concerned that the switch to the lighter oil may be masking a problem that for whatever reason was front-and-center with the heavier stuff? Also, if I remembr right, you have a lot of mileage on your engine (not that that's necessarily a bad thing with these cars!), so are you concerned about the lighter oil doing an adequate job of lubrication, especially here in the Texas heat? Again, I don't mean to alarm or depress you, just wondering...

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[gryphon]

I do think that 5w40 is a bit light weight for a Texas climate and with an engine design that preceeds the use of ultra-low-viscosity oils (and Federal CAFE requirements that contributed to the use low viscosity oils.)



Tom

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[rhudeboye]

[quote name='Cloud9...68' post='39285' date='Aug 1 2007, 08:46 PM']concerned about the lighter oil doing an adequate job of lubrication, especially here in the Texas heat?[/quote]





What would you recommend? In the DC area were in middle of a heat wave w/ temps ranging between 90 - 98 add the humidity and its well above 100.



I'm due for an oil change as well and was debating on what weight to go with for the next 3 months.



Whats optimal for high heat and spirited drives?

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[banditsc]

Redline 10w40 would be a good alternative to M1 15w40.

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[sasilverbullet]

There was a long discussion on www.bobistheoilguy.com about this. The oil guru's there say that Amsoil 5w-40 Euro blend, while a little thinner, lubricates better and lasts longer.



It really does seem to run better, and the oil gurus don't think that running thick oil is necessarily the way to go. Some say (love that phrase!) that the thinner oil actually wicks away the heat better...



I'm going to stick with this oil because it's pure syn, and Mobil 1 isn't anymore.

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[Cloud9...68]

Interesting stuff. I'll have to do some research myself before my next oil change. I switched from Mobil1 15W50 to Redline 15W50, also because I had heard that Mobil1 isn't purely synthetic anymore. While I didn't experience the same dramatic changes in engine behavior as you, the car actually did seem to have a little more pep climbing the hill after turn 8 at Motorsports Ranch (for anyone who's ever been there). I thought it was my imagination, and maybe it still was, but you've got me wondering if a slightly thinner oil wouldn't actually make a tangible difference. Thanks for bringing this up.

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[flash]

i found a noticeable change when i went from mobil 1 15/50 to redline 10/40



1 - my wallet was lighter

2 - i have to drive 15 miles to find it

3 - i have to stock more of it because of number 2

4 - number 1 is exacerbated by number 3



seriously though, my engine does run a bit cooler on the oil temp, and it does seem to spin a bit easier

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[sasilverbullet]

ROFL!!! Flash - you're always good for a laugh!



Also, one of the other "facts" thrown around on the oil forum was that if you run oil that's too thick, it will affect your gas mileage a little.



This is my first tank of gas with the new oil, so I don't have any facts to prove that yet.

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[rhudeboye]

At IMA motorsports they're now using 0W40 M1 on oil changes. I was told that this is what Porsche is now recommending.

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[Renalicious]

Doh! I just bought two cans of M1 15-50. I guess I should be thankful for all these oil leaks, it'll help get rid of it quicker <img src="/forum/images/smilies/968/wink.gif" class="smilie" alt="" />

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[Fox944]

im surprised some of you guys are running 15W50 oil. That is way to thick for our cars.

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[Renalicious]

I've been running M1 10-30 for a long time, but 15-50 was recommended to me so I got a couple of liters.

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[banditsc]

[quote name='Fox944' post='39379' date='Aug 3 2007, 12:53 PM']im surprised some of you guys are running 15W50 oil. That is way to thick for our cars.[/quote]



For those of us in the warmer climates the 20w50 or 15w40 is the reccomended oil per the owners manual. But with a good syn oil like Redline 10w40 is a more suitable oil in the warmer climates.

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[Fox944]

[quote name='banditsc' post='39383' date='Aug 3 2007, 01:44 PM']For those of us in the warmer climates the 20w50 or 15w40 is the reccomended oil per the owners manual. But with a good syn oil like Redline 10w40 is a more suitable oil in the warmer climates.[/quote]





I would never use 15W50 or 20W50 in my car. It is just way to thick imo. Royal Purple 10W30 or 10W40 is what i used in my car.

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[flash]

after talking with redline, and then watching my oil temps, i am convinced that 10-40 seems better for hot street use than the 15-50 was

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[Cloud9...68]

So I wonder where Porsche's recommendation to use the heavier grades came from? And since gaps only grow as the engine ages, I would think you'd want to go even heavier (if that's even possible) as the car gets up into the milesge range of a lot of ours. It sounds like it's a natural-vs-synthetic (which had barely been around when our cars were built) thing.



I do notice that I conseme a moderate amount of oil when driving my car hard, about half to three quarters of a quart during a DE weekend. This discussion has me looking forward to trying a lighter weight at my next oil change, but I guess the consumption factor is my one hesitation.

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[Larry Currie]

I've been running Mobil One 15W50 for sometime. With high mileage on my engine I thought the heaver oil was the right thing to do. Aren't the oils for higher mileage engines alway a heaver oil? Like the one Castrol offers.

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[ds968]

was also thinking about a lighter oil but concerned that the seals which apparently do a great job now at containing the M1 15-50 ( not the slightest hint of a leak anywhere since I bought the car ) may not do so well with the thinner version - so would the cons outweigh the pros ? worth the switch ?



btw, 92k miles on the engine, 80% highway driving ( very often at triple digit speeds ) in northern Ca weather which is pretty moderate for most of the year, as things go.



not sure what do do...

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