[saltydog]

So its been six months since I bought the car, so i went ahead and had the dealer do an oil change, even though it only has 5k miles on it.

So i doubt I will ever get to 8k on the oil, with our current driving style.

 

[DodgeGCaravan]

When was your car built? The oil may have been in the engine for a year or more. 12 months is the limit on my 2013 per the owners' manual regardless of the mileage.

 

[chuzz]

When was your car built? The oil may have been in the engine for a year or more. 12 months is the limit on my 2013 per the owners' manual regardless of the mileage.

That makes absolutely no sense to me at all. Does oil lose something through aging? If so, how come it sits on shelves in parts stores and in boxes in warehouses for years and is still good? I don't get that at all!

 

[Doug D]

That makes absolutely no sense to me at all. Does oil lose something through aging? If so, how come it sits on shelves in parts stores and in boxes in warehouses for years and is still good? I don't get that at all!

Chuzz, yes, oil does have a long shelf life. Not so in an engine.

In an engine, the oil is exposed to moisture and other contaniments - even when it is not run on a daily basis. The oil change interval is based on time or mileage - 6 months or 6,000 miles whichever comes first.

 

[unLIMITED]

That makes absolutely no sense to me at all. Does oil lose something through aging? If so, how come it sits on shelves in parts stores and in boxes in warehouses for years and is still good? I don't get that at all!

Once the oil is exposed to oxygen in the atmosphere or gasoline or other contaminants once the engine has been run the first time it will start to age. In the unopened bottle there is very little air at top so the shelf life is longer.

 

[chuzz]

Thanks for clearing that up guys. As you can tell, I'm no chemist! LOL

 

[Bob Lincoln]

Actually, it has nothing to do with exposure to the air. Once oil has been run in an engine, it contains sulfuric acid, water vapor and other byproducts of combustion. These can slowly attack the bearings and other surfaces. Also, the long chain molecules begin to break down with heat and mileage. So just letting it sit in the engine for a period of time is not good. The fact that engines burn far more cleanly and don't get as much out of tune as in decades past. So the oil doesn't get as dirty, and can go more miles. But it should still be changed every 6 months due to chemical attack.

 

[saltydog]

I know I feel better!