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Hard to argue. :)
 

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Mine burns about 1 quart of M1 5w30 every 3000 miles as well. No smoke, no running problems, no oil on the ground/engine, everything seems fine. Still gets decent mpg too (~25-26). I started the 5w30 at 33K miles and am now at 75K with no noticeable problems, except for dirty hands every 3000 miles. :)
 

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my 96 Cobra with 34k will use a quart of Mobil 5W30 in 3000 miles. No smoke, no leaks, and I have an off road H, so I know that its not the convertors in my case. My compression is good, power is good, no noises or problems (other than transmissions and clutches), mileage hovers around 19-20, but that is my fault as I can get 23 if I really try.
 

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My oil usage seems to be proportional to the amount of "spirit" in my driving, and I like "spirit" in my driving. About 2 quarts between changes.

Also, it's important to check after the engine has been off for a while. I check mine first thing in the morning (I pop the hood when I get home and leave it proped open. That way, in the morning, I'll remember to check the oil first. CRS disease is a biotch :eek: )

I agree with Michael Clements, just keep a watch on the oil level. Get concerned when the car "ain't ridin' right."
 

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2001 Cobra
20,000 miles on it
burn 1 - 1.5 qts per 3,000+/- miles, started around 10,000 miles
Amsoil xl-7500 5w-20
no cats, no smoke, don't think it is a big deal
 

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That's really interesting that you guys w/o cats aren't seeing blue smoke.:confused: Now, it's even more of a mystery as to where it's going? Evaporation?;) Gremlins?
 

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Most likely it's going past the rings. Probably very hard rings that do not seat perfectly. The leak rate is probably so slow that blue smoke is not detectable. This is a Ford thing. My 5.0 88GT had the exact same thing and so did many 5.0 guys I spoke to.
 

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It is in the combustion chamber...

Modern cars have such advanced spark and combustion chamber/piston dynamics that even moderate amounts of oil will burn with practically nothing coming out of the tailpipe. The cat really has nothing to do with it.

Bierbelly:

The vis of 5-dub vs 10-dub 30 isn't significantly different at 100 degrees C. The 10 uses less VI improver, so may have more thermal stability under stress.
 

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Re: It is in the combustion chamber...

Cobra'03 said:
Bierbelly:

The vis of 5-dub vs 10-dub 30 isn't significantly different at 100 degrees C. The 10 uses less VI improver, so may have more thermal stability under stress.
Would it be safe to go to 15w50? Downsides?
 

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Re: Re: It is in the combustion chamber...

bierbelly said:


Would it be safe to go to 15w50? Downsides?
Why even bother? It's a lot easier to add a quart between changes then swap to another viscosity and worry whether or not it will be OK for your engine in the long run.
 

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no cats - smoke

Hmmm... A friend of mine has a 98 cobra NA (runs strong as hell - low 12s on 315 nittos) and we've both noted on each others cars that there is some blue smoke puffing out of both tail pipes when we let *off* the gas. Nothing during acceleration (save for my puff of black smoke in the begining - mmmmm, fuel).

I used to go through quiet a bit of oil (I'm guess more so on a blower car???) but when I switched to mobil 10w40 everything seemed to be okay.

I was surfing around this board a few weeks ago and ran across a post concerning the intake sucking oil in from the valve cover breather tubes. I snagged a URL from there (I can't remember who's page it is - but the pictures were great!!!) and whipped up this little rig on my snake. I'll tell you what, the catcher-tube-thingy is over a third of the way full after only 1 month of weekend driving (maybe 600-700 miles at the most?) As it turns out, there was quiet a bit of oil being sucked into the intake on that tube...

here is the URL to this dudes pictures. Again, they were a great help and I wish I remembered who they were from so credit could be given.

http://www.angelfire.com/sports/home/pcv/thumbnails.html

Ah well...
 

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yeah that's mine.
how's it working for you?

i empty the thing every oil change, usually about 1/2 full.
replace the little filter element every once in a while when it looks real dirty.
Note:
01 Cobra stock vs 01 GT rebuilt
-01 Cobra burns oil and fills separator up
-01 GT didn't burn as much oil and didn't fill separator up as much

Maybe the rings, I used CP pistons and their rings on the GT rebuild. Sounded like a diesel when started cold due to shorter skirt and lighter material of the piston. But it didn't seem to burn oil.
 

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Very interesting....
 

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Re: It is in the combustion chamber...

I was just thinking that it may actually be beneficial to suck a small amount of oil into the intake manifold. The '93-'95 RX-7 twin turbos used to mix oil with the fuel in the injectors at high RPM / WOT. I believe the purpose was to improve lubrication or cooling or something like that. But the point is, they burned oil not due to weak seals, but because the engineers designed oil mix into the fuel injection when the engine was in "balls to the wall" mode.

Maybe that's just a rotary thing, or maybe there could be some benefit on a regular 4-stroke V-8 like the Ford engine.
 

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Re: Re: It is in the combustion chamber...

bierbelly said:


Would it be safe to go to 15w50? Downsides?
Downsides:
1) Less cooling from oil since it will be moving through the engine slower
2) More parasitic drag lessens available power
3) Flow rate may not be enough to maintain adequate lubrication at high rpm
4) Reduced pumpability will cause more rapid consumption of EP additives at cold start
5) Lower MPG

I would just keep pumpin in the oil. Hell, my BB Corvettes went through a quart every 400 miles - these V8's are not Hondas after all!

Micheal Clements: I think the RX-7 wanted to ensure rotor seal life, the great bugaboo of Wankels, so I do not see the idea being applicable to a reciprocating/ piston engine.
 

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Re: It is in the combustion chamber...

Cobra'03 said:
The vis of 5-dub vs 10-dub 30 isn't significantly different at 100 degrees C.
That's correct. Here's the data from Mobil 1:

http://www.mobil.com/mobil_productdata/automotive/passenger/1series.html

Even though the API specification allows a significant ( > 20%) range of viscosity for "30 weight" oils, Mobil 1's 5w30 and 10w30 happen to be very close together in that range.
 

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Re: Re: It is in the combustion chamber...

Michael Clements said:


That's correct. Here's the data from Mobil 1:

http://www.mobil.com/mobil_productdata/automotive/passenger/1series.html

Even though the API specification allows a significant ( > 20%) range of viscosity for "30 weight" oils, Mobil 1's 5w30 and 10w30 happen to be very close together in that range.
Thanks, Michael, I try to be accurate. Hey, where is San Carlos? Is it south of LA? One of my greatest driving experiences was a press-junket where I got to drive a Ferrari Spyder at speed on the Angeles Crest in the late afternoon - long canyon shadows, butterscotch light starting to sink in the West, the browns, tans, and greys of the hills echoing with the frenzied scream of the valvetrain as I hit the red line again, and again, and again....

Jeez, this is getting positively pornographic, but what a day it was! Rank has its privilieges!
 

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Re: Re: Re: It is in the combustion chamber...

Cobra'03 said:

Hey, where is San Carlos? Is it south of LA? One of my greatest driving experiences was a press-junket where I got to drive a Ferrari Spyder at speed on the Angeles Crest in the late afternoon - long canyon shadows, butterscotch light starting to sink in the West, the browns, tans, and greys of the hills echoing with the frenzied scream of the valvetrain as I hit the red line again, and again, and again....
San Carlos is in the SF bay area near Stanford. Your poetic words remind me of many wonderful drives I've had in some great cars (and on some great motorbikes). Of all of those cars and bikes the Panoz puts a huge grin on my face like no other. I drive up Hwy 1 to Mendocino once a month or so for diving and it's 2 hours of exhiliration every time. It's all free diving now; I haven't been scuba diving since I got the Panoz simply because the tanks don't fit in the car and taking the Civic on that road would simply be unacceptable.
 

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Nice...I know that area well also. On the one hand, the Panoz has spoiled you, on the other, you are getting well served by that spoilsport!

A few minutes from my house is Route 711, which winds west through Powhatan County (ancestral home of Pocahontas) and past the site of General Robert E. Lee's last campground before the surrender at Appomatox, now a huge farm field. Great switchbacks, smooth surface, perfect for a torquey V8 ponycar, and formerly my LT1 and NSX - In the Fall, there is the Blue Ridge Parkway, winding from Crozet (Walton's Mtn) down to the Smokies in Carolina - amazing drive, when the bears and the tourists are sleeping (hint: 5:30 a.m. to sunrise).

I say, you drive East, I drive West, we meet - uh - Des Moines?
 
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