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View Full Version : Motor oil grade to run in Cobra


SlowSVT
08-05-2004, 09:21 PM
What are your thoughts on running a hevier oil other then the 5-20 weight Ford recommends? 5-20 seems awfully "thin"(water has the viscosity of "0"). My understanding is that a hevier weight oil let say a 10-40 or even a 20-50 has a higher film strength and will provide more cushion the bearing and will stick to surfaces better. The thicker oil will cause more drag on the piston rings and will reduce the fuel milage somewhat. I've been running 20-50 in my Subaru since day one and the engine runs excellent with 230K miles on the clock. I know lots of new cars recommend 5-20 weight oil but my thinking on that is that it's an easy way to squeeze more MPG which is a good selling point. If "not" could someone tell me why it's "bad" to run a hevier oil then 5-20. Thanks

Russ

redsnake99
08-05-2004, 10:32 PM
I run 5W30 Mobil 1 Synthetic oil in my 99 Cobra. I have since I bought it when it had 10,000 miles on it. Now has 110,400 miles on it. Supercharger takes about 1/2 qt, altogether takes 6 1/2 Qts. I change oil every 5000 miles.

Works for me.

cobrabitn
08-05-2004, 11:14 PM
It's called tolerances. You run a thiner oil because the tolerances are much more tighter then a car that requires a thicker oil. I would never run anything then the manufacturer's recommended viscosity so a warranty will not be voided. Yes, your warranty can/may be voided on the engine if you are running the wrong type oil viscosity. Also, the second reason is cold start up. You do not want to have a thick oil in there for a cold start up as this will most likely cause premature wear on the bearings and other lubricated components of your engine. Best thing to do, use the recommended weight and you won't have to worry about warranty issues since this seems to be a big issue in today's society.

Tony

cobracrazy
08-06-2004, 09:09 AM
Exactly what Tony said-
Older car motors did not have the tolerances that today engines have. The orifices and oil journals are smaller. If you run thick oil it will be possible for certian critical locations to not get enough lubrication. I highly recomend that you stick with factory specs.

My 0.02$ :)

Mirage
08-06-2004, 02:37 PM
SlowSVT~ I broke my '03 Cobra motor in on regular dino oil, did the first oil change with the recommended standard and then switched to Castrol Syntec. the key difference is of course full synthetic but I kept the correct viscosity (5W-20). I've done this with my previous Cobra and all of my motorcycles. I'm currently at 6,000 miles and enjoying every minute of it. :)

SlowSVT
08-06-2004, 08:34 PM
I've been poking around on the net regarding this subject. The conclusion I get is the run the full synthetic 5-20 weight oil. Looking at Amsoil in particular. Anyone recommendation on what brand of synthetic?

Thanks guys

Russ

RF Cobra
08-07-2004, 12:36 AM
Not the exact answer you are looking for, but any name brand synthetic that meets/exceeds Ford's specs will work. I would suggest avoiding the "blended" oils as they are a waste of money in my opinion since you are still getting 50% + dino oil and the objective is to provide a cleaner oil when using synthetic. Go with a known brand that you feel comfortable with, and if it has a cheaper price too then that is an added bonus. :)

I've seen people post on other boards that use Amsoil and never saw any complaints about it. Personally, I've used Mobil 1 and Havoline (full synthetic version) and usually based my choice on which one was cheaper at the time since the stores I buy from like to keeping swapping the prices back and forth between them.

I've been poking around on the net regarding this subject. The conclusion I get is the run the full synthetic 5-20 weight oil. Looking at Amsoil in particular. Anyone recommendation on what brand of synthetic?

Thanks guys

Russ

JTSVT
08-25-2004, 05:54 PM
I went w/ the recommended Motocraft (dealer-used) 5w20 all synthetic...along w/ Motocraft oil filter......figure Ill keep what the makers suggest;) Hope I did right---JT

beerkat
08-25-2004, 07:20 PM
Syntec 5w20:thumbsup: