Synthetic or Fossil Oil?????

[ItalianSVT]

Hey guys I bought the Cobra(since Nov.05) and needless to say have yet to put 3000 miles on it but I am not sure when the previous owner changed the oil last. So, What type of oil do most of you run throught the year? Just want some input as to what types are the most popular and safest.
Thanks
Derek

 

[Tom's_03SVT]

mobil 5-20

 

[ShelbyGuy]

everything you need to know is either in the owners manual or printed on the oil fill cap.

at just under 52,000 miles i sent a sample of my oil to the lab (blackstone) the other day. i should get the results back today or tomorrow. i'll post them.

on these engines its the machining of the internal passages that determines the weight of oil used. you may have noticed that all of the cars with the ford gt/00r/grand-am cup/new gt500 heads gets a 50 weight oil, but none of the 4.6 cars do. its not just for fuel economy. its because the engine has some seriously tight clearances.

thats not to say they're sensitive to what oil you run, because they are not. you want a car thats sensitive to motor oil? try a pump düse volkswagen diesel. you can run 5w-30 or 10w-30 without damaging anything in the grand scheme of things. heck ive been known to run 0w-20 in the coldest periods of chicagoland winters.

ive tried a few different weights and came back to 5w-20.

 

[ItalianSVT]

Thanks

I realize the owners manual will tell me but from my experiences with different engines some do not react well to synthetic like RX-7's and TT Mitsu's(tend to spin main bearings). So, it was better to ask for some input, guessing could be bad.
Thanks

 

[SnakeBit]

Synthetic all the way. It works.
My favorites are Mobile 1 and Amsoil. Mobile 1 is cheaper and more available.

Currently, I'm running Amsoil 0W30. I change the filter and top off every 3,000 miles. Every 6,000 I pull a sample and send it off to Blackstone for analysis. Evey 12,000 I drain the pan and put in fresh oil with a fresh filter (Motorcraft filters).

Last sample I sent in after 12K miles came back saying the oil was good. Amsoil would prefer that I send them a sample and they will tell me when it needs to be changed, but I don't drive the 03 much any more (I have a more economical DD), so I figure 12K is good enough. The main problem with extended oil changes is contamination (mainly from antifreeze or gas), but as long as you have it tested regularly, then it is fairly safe. The filters are not meant to go that long, so changing the filter and topping off every 3K is a must. As the engine ages, I will send a sample off for testing with every filter change. I ran my 86 GT like that for 10 years and over 200K miles and the engine was still running strong. In fact, as that engine aged, it used less oil, and that was on Castrol Syntec. IMO, Mobile 1 and Amsoil are a better oil.

 

[CobraBob]

Great advice above. I, however, always used the weight recommended in the Owner's Manual. I used Mobil 1 for a period of 3 months and then switched back to Ford's synthetic blend. I used the synthetic blend basically for the entire time I owned it. I did, though, change the oil religiously every 3 months or 2K miles, whichever came first. Personally I believe the frequency of changes is more important than messing with the weight. Which is why I chose to stick to the recommended weight and change the oil frequently.

 

[03SoCalCobra]

I've tried most combinations of the major oils and filters in the past 4 years and 85,000 miles or so.

The oils each have a different effect on noise coming from the motor. Some oils like Moble 1, make the engine seem a tad quieter for noises in the high frequency tapping range; this oil seems to get dirtier faster than the others too, not sure why. Amsoil is just the opposite, you seem to hear everything; this oil seems to stay cleaner longer (visually and smell). Royal Purple is about the same as Moble1; Redline seems to be the best all around oil IMHO; noise is about in the middle, doesn't get as dirty as fast as M1. I've only used the Ford synthetic once and it was very good all around oil; i'd probably reach for it before the M1.

Filters make a BIG difference. Cheapie Fram filters (which I rate about the same as Jiffy Lube) and it's dirty after 3k miles. Better Puerolator filters and it's 5k. Really good Moble 1/Amsoil filters and it's still dark honey at 5 or so instead of black- that says something about the importance of the filter.

To make the same point brought up earlier- it's the oil getting contaminated with either particulate matter or gas that requires it to be changed.

 

[MikeW]

I see that you are in Knoxville.... Did you buy the new heads local and did you install them yourself? I'm looking to get the 05 heads soon so any advice that you can give would be most helpful.


THanks,
MIke

 

[Hicompression]

Fossil oil all the way! I bought the car new in June 2002. I run Castrol 5W-20 Dino oil or Motorcraft Synthetic blend 5W-20. Full synthetic is just a waste of money. I like to stick to a 3 month or 3 thousand mile oil change interval. Full synthetic just doesn't make economic sense a this frequency.

 

[04torchred]

Great advice above. I, however, always used the weight recommended in the Owner's Manual. I used Mobil 1 for a period of 3 months and then switched back to Ford's synthetic blend. I used the synthetic blend basically for the entire time I owned it. I did, though, change the oil religiously every 3 months or 2K miles, whichever came first. Personally I believe the frequency of changes is more important than messing with the weight. Which is why I chose to stick to the recommended weight and change the oil frequently.

In all fairness changing the oil really early is just a waste of money if you are running a full synthetic, it will not be broken down by then.

I run 0W-30 in the winter and spring and when I do an oil change in the summer I put in 5W-30. The 0W-30 is a very good oil. I use Mobil 1, Amsoil is crap IMHO, too many addative packs that they claim makes it last longer. Synthetic oil base stock comes from two major companies, so after that it is just add packs!