Alright guys, I searched in this forum and the engine forum but couldn't find anything that I needed.

I'm looking for the time that oil stays in your engine before it needs to be changed. I guess what i'm looking for is how long before oil breaks down. Reason being is that I changed my oil in June and have yet to break 3000 miles on it. Last time i changed I put MC 5w-20 and the Fl820-S filter. I asked my dealer and they said it needs it every 3 months. My personal mechanic said it would be good for almost a year if it wasn't driven hard. While every 3 months seems extreme, 12 months seems far out. What is a happy medium?

 

I'd go 6 months/3000mi whatever comes 1st. I used that interval on a 5.0 Mustang LX I used to have, cause it was more of a garage qween, & did not see many miles.........

 

I agree; I only put about 3K on my truck a year, and I usually change the oil every 4 - 6 months.

 

Its my understanding that engine heat and gases can break down the viscosity of motor oil which is the basis behind the 3months/3000mile rule with conventional oil.

Ponder this. For some people its possible to drive their vehicles only 20miles/day, which over a 3month period is only about 2200miles. However, depending on traffic conditions this may mean the engine is running for 2 hours each day in stop-n-go traffic. It would be this condition that would diminish the lubrication properties of your motor oil. So while not driven 3000 miles according to the odometer, the engine oil has been exposed to about 224 hours of wear and tear. 224 hours at a conservative average of 40mph would equal about 8960miles over a 3 month period, which would far exceed the recommended interval for conventional motor oils.

Hope this helps.

 

That is helpful, but my truck is not my daily driver. It only gets driven once or twice on the weekends and its usually just around town or on dates and stuff.

 

If this will continue to be the situation for a long time to come, then you'd probably do well to have a UOA (used oil analysis) done. Siphon it out of the filler tube without draining the oil... I'd probably start at the 6-month mark, and go from there. The UOA will give you usefull info on the longevity of your oil. If the UOA says that your oil is still doing well at 6 months, then send in another at, say, 9 months... Same thing, if it's ok, then do a final sample at 12 months when you finally change your oil. Yes it will cost you about $20 per UOA, but it will be worth it if your situation stays the same for years to come (not daily driver, low miles, etc). That way, for years to come, you will already have a reasonable, scientific estimate on how long your oil will last in your circumstances.

Plus, an occasional UOA tells you lots more than just how your oil is holding up. It gives you indications of how well your motor is wearing, tells you about any coolant contamination, fuel dilution, oil filter performance, air filter efficiency, etc. Definately worth the $20 IMO.

 

I change my synthetic every 5000 miles... comes almost almost as clean as it went in.

 

i use AMSOIL full synthetic and i get the same results. clean as the day it came in

 

I have always done about 6 mounths on my old truck, it was driven as an extra car when I needed a truck. My 04 I drive everyday and I change the oil every month. I hit about 3500 miles per month

 

How would one go about siphoning out of the filler tube? Is a UOA something that can be done locally or does it have to be shipped off?

 

Im pretty sure Ford recommends 5000mi if your using Motor Craft Synthetic blend 5w-20.

If you are using regular oil and you only drive it once in a while then I would say not more than 6mo

 

I get thats its supposed to be every 5K miles but how long time wise is it good for because it might be 12 months before i reach 5K miles

 

I've always changed my oil at the recommended mileage (5000). Normally, that's only once a year in many of my trucks.

Technically, oil doesn't break down. It may burn off. It may get full of crud from use. But, the carbon chains remain intact. The polymer and other additives eventually wear out, but that's from prolonged use and heat. I don't buy any argument I've heard so far that oil somehow goes bad sitting in the pan. I don't see any "best if used before" expiration dates on quarts of oil...

 

I use Mobil 1 full synthetic and change it every 6-8k, which equates to about every 2-3 months for me.

 

I would swap to synthetic and do 6month or 5k intervals. I have done this with my last 3 vehicles totalling over 250k without a problem