Whatever formula gets an 02 Boxster to 234K miles works for me!

 

And what would that "formula" be, again?

 

I've been using synthetic oil since Mobile 1 came out in the mid-70s. Originally they had studies where they ran an engine continuously for the equivalent of 100K miles without a change, and when they stripped it down there was minimal wear. But the key thing there was the engine ran continuously, and in a laboratory environment. I spoke with an automotive engineer who specialized in engine design and he told me that while it's true that synthetic oil doesn't break down as rapidly as traditional oil, the oil type has no effect on how quickly the oil filter gets dirty. He said the oil could retain its properties to 20000 miles, but if it has bits of metal in it there's going to be increased wear. Since the filter normally holds about a quart, it doesn't make sense to change the filter and add a quart of new oil vs doing a complete oil and filter change.

Also, he said synthetic oil has no effect on the accumulation of moisture condensation in the crankcase, so if the car sits for periods of time, or is driven in short hops where the condensation doesn't completely vaporize, then more frequent oil changes are advised. He said that a 10K oil-change interval has a completely different outcome for a car that sees 20K/year vs one that only sees 5K/year. In the latter case, time becomes a more important factor.

I put around 5K/yr on mine so once/yr oil change is what I normally do. However my local Porsche dealer sent me a coupon for a free oil/filter change so I just had it done although I'd done it 6 months/2500mi ago. Can't beat that. (They use Penzoil Synthetic 5W-40 instead of Mobile 1 0-40.)

 

To those reasons (engine wear/moisture) I add, E10 engine corrosion and E10 contamination of oil. That's why I change at 5-6k miles. If I was on a continuous 10k mile road-trip I would not change oil in mid-trip. The use pattern is part of the decision.

 

Most of the information on this thread focuses on the amount of mileage between oil changes. In my case, my new to me 2006 S Cab is not a daily driver and I only put about 4,500 miles on the car in the past 18 months. The oil was changed and a full service done when I purchased the car at the end of 2012 (at which time it had 17,500 miles).
So, is it necessary to change the oil after a year even if I put so few miles on it, or can I wait longer time intervals? Thanks in advance for any advice.

- SMR

 

You need to change the oil at least once per year.

 

Since I've retired I only put about 10,000 miles a year on my '09. There are times in the winter where it sits for a month or more. I change based on the calendar, not the odometer. Every April and every October it gets an oil change with Mobil 1 0-40. And, I don't really care what others do.

 

Sniff. Now you've gone and hurt my feelings

Actually 2x a year works for me also. In addition I have switched to grade 5 Motul 5w-40. But that's another annoying thread. Cheers,

Gerry

 

I changed the oil on my 997.2 every 7500 miles just for peace of mind. I'm sure changing every 10,000 would be just as effective. It's just a mental block for me to wait longer than 7500 mi.

 

Anecdotal evidence is entertaining. I will entertain.

I change my oil at the max recommended. Since 1985. Turbos... high output... family cars... pickups towing 11,000 pounds... and even the 300k mile 928 that finally had a tired engine. My goal is 200k plus miles. Always get there. Never had an oil related problem on any car from Germany, Japan or the USA.

Storing a car? Change the damn oil.

Otherwise... drive that ****.... and wind that engine out every damn time.

 

The manual for the 06 says every 20K or 2 years, whichever comes first. Given the limited driving I've done (but each trip is a decent drive, including highway speeds), I think I am going to wait 2 years (which will be in my case something like 8,000 miles max).
Thanks for all the advice and suggestions.

 

Funny.

 

I drive 3K miles a year and change the oil once a year. The additives do age and become less effective.

Regards,
CF

 

Lots of speculation, superstition, and wild-*** guesswork in this thread. A $25 oil analysis will remove any doubt and give you good details about the health of your engine, too.

 

If anything you can change the oil frequently and save the receipts. I bet this helps at resale and you get every penny back plus interest when the next owner sees how well it was cared for. I would not hesitate to plan every 3-5K, that way if you forget or if something comes up the interval will still look good.