Carpokes Porsche Forum

On the flip side of the extended mileages, there is still the time interval of 12 (No. Amercica) or 24 months (EU). I don't know about the rest of you, but I don't drive enough miles per year to get to the mileage limit on ANY of my vehicles. All of them get changed by time, once per year.

Arne2 wrote: Fri Apr 07, 2023 12:23 pm On the flip side of the extended mileages, there is still the time interval of 12 (No. Amercica) or 24 months (EU). I don't know about the rest of you, but I don't drive enough miles per year to get to the mileage limit on ANY of my vehicles. All of them get changed by time, once per year.

Likewise for me regarding the 12-months occurring before the 10k miles.

But, same as Tom, I like to change oil/filter more often than called for, especially for anything driven hard or in harsh conditions, another situation to take into consideration.

Since I have too much spare time on my hands I will relate a story about engine wear.

I had a professor in college (mechanical engineering class) who had worked for Rolls Royce Aero Engines.

He told the story about Rolls Royce Merlin Engines (12 cylinder 27 liter 1000 plus hp) used in the Spitfire during
World War II.

To expand capacity, during the war, these engines were also built under license by Packard in the US.

I gather aircraft engines typically get maintenance based on flying hours.

Engines, both UK assembled and US assembled, would undergo maintenance at the same prescribed number of flying hours.

What was seen when the engines were disassembled and inspected was far more wear, "failure" and replacement components needed in the US engines than the UK engines.

Keep in mind the engines were all built to the same specifications and using identical engineering drawings.

The increased wear factor caused concern so the issue was investigated.

The cause was identified as follows:

All components were designed with the requisite engineering tolerances, so as an example the engine block cylinder bore could be plus or minus 10 thou' - similarly a piston could be plus or minus 10 thou'.

The UK Rolls Royce assemblers had an unwritten work practice of selecting components that essentially "blue printed" the engine - so for example they would measure the cylinder bore and select and optimize a piston for that cylinder. This had the effect of minimizing assembly tolerances resulting in less engine wear for given hours of flight,

The US assemblers simply assembled an engine with whatever required components were at hand. No one ever told them to selectively choose components to minimize wear.

Interesting story, at the time, for a budding engineer wet behind the ears

audi4t wrote: Fri Apr 07, 2023 12:18 pm Tom

I don’t think there is a right or wrong answer and obviously oil changes sooner rather than later should be beneficial most of the time.

I’ve experienced a tech not tightening the drain plug after an oil change and oil leaking, but that’s another issue

However, it’s of no benefit for a manufacturer to extend oil change intervals if they aren’t confident the motor and oil are capable.


Turbos do operate at high temps and my 2008 BMW 135i is a straight 6 tru twin turbo not the later biturbo - it now has 73,000 miles on the odo and doesn’t burn a drop of oil.

Long time ago a good friend took his brand new Toyota 4x4 to a quickie lube place (!!) for a quick break-in oil change. They crossed threaded the oil plug and it fell out on the highway, and they ended up paying for a replacement motor! So, yeah, I guess there are risks either way. My brother's F150 calls for new spark plugs at 100k miles. They started to miss around 30k . The going belief is that Ford wanted to promote their car as virtually maintenance-free for the first 100k... (Re BMW maintenance, I had a 2000 323ci that I put 130k on, and then gave to a family member who ran it up to 240k. When he ended up selling it, it still had the factory clutch!)