Change oil or wait?

[911monty]

Originally Posted by dghii

Don't change your oil after only 1100 miles of street use. You're fine.

Drive your car more!

At face value I disagree, 1100 miles in 7 months is roughly 40 miles a week which is worst case for oil use. Frequent short trips never brings the fluids up to operating temp long enough to boil off contaminates. This is considered severe duty and actually requires shorter oil change intervals.
Now if you've only driven twice for 550miles in 7 months then the year interval is fine.
Get out and drive the car more!

Definitely get the oil analysis done.

[Fyeganeh]

Originally Posted by 911monty

At face value I disagree, 1100 miles in 7 months is roughly 40 miles a week which is worst case for oil use. Frequent short trips never brings the fluids up to operating temp long enough to boil off contaminates. This is considered severe duty and actually requires shorter oil change intervals.
Now if you've only driven twice for 550miles in 7 months then the year interval is fine.
Get out and drive the car more!

Definitely get the oil analysis done.

Well I didn't drive it over the winter and I drive about 15 minutes to work - 6.5 miles -and same back home. The temp gets up to the 180 mark but only for about 5 minutes each way. Longer distances are rarer - once a month or longer.

[10/10ths]

DUDE....If you are only firing her up and driving her 15 minutes at a time, you MUST change the oil every 6 months.

Your oil is not getting hot enough to burn out the impurities that accumulate from piston ring blow-by. Your rings don't get hot enough to completely seat the cylinder walls in fifteen minutes, so every time you drive that car for such a short period, you are loading the oil with exhaust contaminants.

These contaminants sit in the sump and acidify overnight as the air cools and condensation forms, leading to acid in the sump which is eating away at your engine right this minute. You are creating an acidic fluid that is inside your sump and eating every bit of metal like a cancer. You need to drive her for at least thirty minutes at a time once a week and burn that stuff outta there.

And change your oil every six months.

Oil is cheap.

H6 engines are expensive.

Brown bag it if you have to.

Good luck.

[njbray]

I always say if you are not going to drive the car far enough for it to properly warm up - don't bother taking the P car at all! It's better to let it sit until a longer trip.
If you never go on longer trips (at least 50 miles?) is it worth having that car at all?
Go and have some fun and give the car a good drive - then it makes it worth the oil change!

[Fyeganeh]

Originally Posted by njbray

I always say if you are not going to drive the car far enough for it to properly warm up - don't bother taking the P car at all! It's better to let it sit until a longer trip.
If you never go on longer trips (at least 50 miles?) is it worth having that car at all?
Go and have some fun and give the car a good drive - then it makes it worth the oil change!

Well a couple of points.... the money isn't really the concern, it's more a question of is it overkill to change high grade synthetic oil after only 1100 miles of use when the manual says you only need to change once a year or 10,000 miles.

The question moreso was one of burning off water and contaminants - I've heard that a lot on here. The reality is that the oil gets as hot in my 15 minute commutes as it does on my 1 hour trips to D.C. On the one hour trip, it's at that temp for 50 minutes and on the 15 minutes it's at that temp for at least 5 minutes. But then it sits in a garage where it's likely close to that temp for another 10-15 minutes before it cools off. So how long does it need to be at that temp? If you do only a 5 minute commute you never reach the highest temp. Is just reaching the highest temp good enough? If not, how long at the highest temp is required to "clean" the oil? Aside from the contaminants, it doesn't make sense that a high grade synthetic oil should wear out after only 1100 miles.... but that's why I asked the question- to learn from everyone.

As for having fun with the car, I've had plenty of fun with it and enjoyed it a ton since buying it new 17 years ago. I've taken it to the track multiple times and used to drive it 12,000 miles a year, but times change as you get a growing family and move. It now has about 65,800 miles on it and it so happens that I live close to my work so my commute is short. Driving to work with the top down five days a week in the winding backside country roads is plenty of fun whether spring, summer or fall :-) and I don't miss the congested highways. My long distance travel typically involves 4 people now and so the Boxster doesn't cut it most of the time when there are longer commutes :-(

[911monty]

Your temp gage indicates coolant temp (water) and heats up to 180 deg relatively quickly with a closed T-stat as it pulls the heat of combustion from the cylinders. Motor Oil conducts and transfers heat much slower and while it does conduct residual heat from the cylinders the majority of the combustion heat goes into the coolant. During this time the oil cooler is actually an oil heater. I believe it is generally accepted that the motor oil and engine block take a minimum~15 to 20 minutes to come up to operating temp. It takes a while to heat 2 gallons of oil. I really wish the oil temp (from the dipstick probe) was indicated on the dash.

[Pdwight]

My Pcar gets about 4K miles a year, I change the oil mid summer and then at the end of October...regardless of miles