DOES THE ENGINE OIL IN A CAR EXPIRE ?
My grandma has a 1990 3 SERIES BMW 6 CYL which was given to her by one of my uncles. My grandma only does about 1000 miles a year for the past 6 years. Most of her trips are to the grocessary store and church both of which are about a combined trip of 90 miles a year. I want to know how often the oil should be changed as I am going to live with her for the nex 18 months.The garage guys change the oil for her every 6 months as she always insist they do it.
Comments
Because your Grandma is only doing very short trips, the engine oil has to work a lot harder.
Most of the wear to an engine occurs in the first ten minutes of a trip, before the engine has warmed up to operating temperature and before the oil has started to flow smoothly around the bearings.
As all your trips end before the oil has had a chance to warm up properly, all the water and products of combustion that condense in cold engine oil (forming mayonnaise under the filler cap) remain in the oil and cause it to deteriorate. In the worst cases, acid can form which attacks the metal surfaces. You will never damage an engine by changing the oil too frequently.
I don't quite understand your figures, should that 90 miles a year be 900 or is the return, combined trip 90miles?
In your case, if she only does one thousand miles per year, I would say that an annual change with a good quality oil should be adequate.
She's doing the right thing with the oil. It could be in the engine three years and still be OK, but her slight use of the car means running a cold engine all the time and water etc may accumulate.
Take a 30 - 50 mile run every 3 months at highway speed to get the engine hot and pump out condensation from it and the exhaust system, also charges the battery.
The oil expire in the bottom of the bottle they have the expiration date.But remenber you have to change the oil by the color the oil change whit the constant use of the car. In a normal regular car that you drive every day to work and do all other relating things of taking care of the house.Including going to the doctos and other personal daily routine and exeed of 3000 miles every 3 months.You should change the oil every 3 months.
Like your Grandma that only use the car just to go groceries and church adding this to 1000 miles a year. She is doing fine by having the oil change every 6 months,because she is not runing the car that much .The important thing is to keep the car in good shape taking good care of it.
Short trips mean that pollutants, such as fuel and water condensate do not burn off readily as the oil is at low temperature most of the time.
So frequent changes are a good idea. As has been said, synthetic oils are better all round at coping with these, and other, conditions. Although they are quite expensive, the protection lasts longer.
I would have thought that BMW would recommend at least semi synthetic if not fully synthetic. With fully synthetic I would think you could safely go to annual oil changes.
From the sounds of it, keep changing it every 6 months. Engine oil does many things. It has detergents that keep sludge from forming and sticking to parts. It has anti foaming agents. Theses additives get vapor-ed off with time. The oil also keeps products of combustion,moister,and other detrimental stuff in suspension,so,they are removed when you change the oil. Short trips,are the worst thing for engines and the oil.The engine oil does not get hot enough to boil off moister and suspended gasses.That's where sludge forms from. Don't forget about antifreeze too. just because it's green doesn't mean it's good. It also has additives that get vapor-ed off in time.
Engine oil does deteriorate in use, especially when it seldom if ever get warm enough to boil off any impurities. 6 months is fine with modern oils, I expect she gets them to check it over for her at the same time. Can you persuade her to let it go for a good, fast run now and then? That'll help clear the cobwebs too. It'll probably start and run better after that.
"1,000 Miles a Year??" In a way that would be considered "Sever Driving!" Yeah Motor Oils do have a "Life Span". 6 Months is GOOD but between trips (Sitting that long) the engine does go "Dry of Oil" on moving parts. She'd be better of with a "Full Synthetic" that Flows Faster on Start-up for better protection of engine parts.
What are you people like? - oil expires!
Its millions of years old before you get hold of it so a couple of extra years isn't going to harm it much.
It DOES get dirty and that's what filters are for.
98% of recovered oil is filtered and cleaned and reused.
I would be far more concerned of using a piece of Germanys technical excellence as a shopping trolley and the excessive wear and tear on the rest of the components.
Your granny would be far better advised to sell the beemer and invest in a far smaller and more economical car - something like a Micra or equivalent shopping hatch.
The oil companies naturally want you to buy more oil. So they recommend you change it every three months. They have somewhat succeeded in brainwashing the public into believing this. And you'll see that reflected here. But this is not necessary to change oil solely on it's age in the engine. I would have to agree with the six months though. The problem isn't that the oil is getting dirty from your Grandma's driving. But, it is probably getting quite a bit of water in it from condensation. And she doesn't drive the car enough to truly warm up the engine long enough to dissipate the water from the crankcase.
Generally for regular engine oil its 3000 miles and for synthetic oil its about 5000 miles. the thing is that when oil is used in a motor it usually collects little pieces of metal that sit at the bottom of the oil tank and when ran gets filtered through again but usually gets caught on the drain plug that usually has a magnetic tip. But the additives in oil usually breakdown after so long which makes the oil become weaker. so yes i would change it about every six months it wouldn't hurt the car at all.