[Everett II]

What do you use to determine when to change your oil? I changed the oil in my Cobra in January, and have put 1002 miles on her since then. I drive the car once a week usually between 50 to 150 miles. The oil appears clean. I use Castrol Syntec 5w-30. I was changing the oil every 3 months prior to the switch to Syntec, no matter how few miles I had on it. Even the dino-oil was staying clean. Would it be ok to extend the oil change to 3000 miles and leave the oil in longer?

Thanx, Everett.

[302 Z28]

It really comes down to what you can afford. You certainly are not doing any harm in changing it too often. The fact that you do not drive the car that often would tend to make me change it based on time rather than mileage.

Vince

[busterwivell]

I've always done the oil changes for my toys every time the seasons change, ragardless of the mileage. The daily drivers get it every 3000. I've always done it, and it hasn't hurt me any. I know others who will do it once a year with their toys. I'm no expert on oil and contaminents, but I suspect oil, just sitting in the pan for a year, would somehow break down some. Again, that's just me, but I tend to try to stay on the safe side.
Bill

[ChevelleSS_LS6]

Originally Posted by 302 Z28

It really comes down to what you can afford. You certainly are not doing any harm in changing it too often. The fact that you do not drive the car that often would tend to make me change it based on time rather than mileage.

Vince

especially true... condensation tends to build up on the inside of engines after a while

[Irelands child]

Originally Posted by busterwivell

I've always done the oil changes for my toys every time the seasons change, ragardless of the mileage. The daily drivers get it every 3000. I've always done it, and it hasn't hurt me any. I know others who will do it once a year with their toys. I'm no expert on oil and contaminents, but I suspect oil, just sitting in the pan for a year, would somehow break down some. Again, that's just me, but I tend to try to stay on the safe side.
Bill

I'm not sure what vintage Cobra/engine you have but the old rule of thumb used to be 3000 miles or 90 days. With the mileage you drive - I personally would probably go back to changing as the seasons change. While the oil may look like new, it still contains contaminants - by products of combustion which are unburned hydrocarbons, water and gasoline additives. It will also contain other moisture from temperature changes and humidity. Another thing I would do is to do some research on brands - Mobil 1, Amsoil and Royal Purple synthetics are generally rated better then Castrol though you might not need the syn oil if you increase your oil changes .

Dave

[mosstrooper]

I change mine every 10 years, whether it needs it or not.

[JohnNGa]

Originally Posted by mosstrooper

I change mine every 10 years, whether it needs it or not.

Somewhere between mosstrooper and busterwivell is a happy medium. Right now I only have daily drivers (my toys r under construction), but I have changed all my cars/trucks at 5,000 miles for about 15 years now. I used to change at 3,000, (and even 2,000 on things driven hard). But years ago I just decided I was spending too much on oil and filters and came up with a 5,000 mile interval. One logic (for my aging, forgetful brain) was it is easy to remember. I change at even 5s, 25,000, 30,000, 35,000 etc. I never have to write it down anymore, I just glance at the odometer and If it is close (within 500-1000 miles) of an even 5,000 mile increment, I change oil and filter (always both) as soon as is convenient. If I go a few miles over, I don't sweat it. In all these years of doing this, I have never had an internal engine failure I could attribute to lubrication problems (broken valve springs in BB chevy's don't count, that's just the nature of the beast).

As far as a low mileage car goes, there is a greater concern with condensation. I say greater, because condensation can, and does happen in the crankcase of a vehicle that was driven all day one day and sat for all the next day. Once the engine cools off, and air temp and humidity are right (cold metal and high humidity=condensation) there is the potential for the metal to become damp. The difference between occasional driving and daily driving is the daily driver engine is heated up often enough to boil the water out of the oil and off internal engine surfaces before it accumulates enough to affect the lubricity of the oil. In the occasional driver the water can (not always, but can) accumulate enough over time to run down into the oil. Water is heavier than oil, so if it condenses enough to run down the inside of the pan, when it gets to the surface of the oil, it takes a dive to the bottom. Guess where you oil pump pickup is? The result is the water can get "mixed" with the oil, which affects the lubricity of the oil. So how often do I change occasionally driven toys? No more than once a year because I have always driven such cars often enough to feel like condensation was not a problem. Even if I don't drive em, I start 'em up and warm the engine before I shut 'em down. If I start one to just move it out of the way, I always let it run long enough to get warmed up, that boils off any moisture in the crankcase as well as dries out the exhaust system. Once a season, that's too often for me, but it's your money, and more importantly, your peace of mind.
My 2c, and appologies for being so long winded. Now that I have bragged about no engine problems, tomorrow my 75,000 mile pickup (oops, time to change oil!) will probably sling a rod!!

[techinspector1]

At the outside, oil changes are recommended every 6 months regardless of mileage.

Like John, I don't write anything down, I just change at 2,500 miles. 2,500, 5,000, 7,500, 10,000, 12,500, 15,000. You don't have to write it down or remember anything. You DO have to look at the odometer once in a while though.

[Rick WI]

That oil should go 5000 miles no problem.