Oil change every 5000km?

[dnp_now]

Hello everyone.

I live in Costa Rica, where the gas is not very "high" quality. So I bring my x5 4.4 2003 to fix the A/C and the service guy tells me I should change my oil. I just changed it with them last Nov 05, and have driven only 6000km since then.

He tells me that I should change my oil every 5000km, since the quality of the gasoline here is bad. Me coming from the states, where an oil change every 10,000 to 15,000 miles is the norm. Every 5000km oil change sounds excessive, especially when they charge me over $100 for an oil change.

What do you think?

[SuperGreg]

Originally Posted by dnp_now

Hello everyone.

I live in Costa Rica, where the gas is not very "high" quality. So I bring my x5 4.4 2003 to fix the A/C and the service guy tells me I should change my oil. I just changed it with them last Nov 05, and have driven only 6000km since then.

He tells me that I should change my oil every 5000km, since the quality of the gasoline here is bad. Me coming from the states, where an oil change every 10,000 to 15,000 miles is the norm. Every 5000km oil change sounds excessive, especially when they charge me over $100 for an oil change.

What do you think?

Not needed with synthetic oil. Curious, what does low quality gas have to do with oil changes?

[X5Andrew]

Not sure, but I think it has to do with the crank case gases.

[Lambeau]

If fuel burns efficiently in the combustion chamber there is little or no residual remaining in the chamber as it is consumed in the "explosion". If fuel is poor there may be a very small amount that remains in the chamber and may remain on the cylinder walls and eventually get past the rings and into the crankcase. Rings do not seal 100% (but there are "zero-gap" rings that do approach 100% efficiency and I use them on my 67 Chevelle SS 427) and the oil in the crankcase can get contaminated with fuel byproducts that are not burned.

[cary]

The quality of the gas should not effect blowby. What it will do, depending on what is bad about the gas, is plug injectors, cause carbon buildup on the valves and pistons, and potentially (unlikely) if the gas is really bad quality erode the cylinder walls. Except for the last item, none of these will result in excess fuel in the oil (a really plugged injector could, but the car would be running pretty poorly at that point).

A prudent interval to change your oil would be 10,000 km intervals with a quality synthetic.