Official 997.2 service intervals too long?

[pothole]

997.2 (and .1 obvs) service interval is 20k miles. Consequence is that the history of quite a few cars show first service at a large fraction of 20k miles. To me that seems nuts - to go 15-20k on the factory oil with a brand new engine.

Makes me wonder about the implications for high mileage longevity of cars that had long initial service intervals. I wouldn't be happy leaving it anywhere near 20k on a normal service let alone for the first one when running an engine in. But maybe I'm too ***** and actually really doesn't matter.

 

[Slayer]

Depends on the owner.. some like to keep changing with the theory that it's better for the engine, others stick to the Porsche recommendation.

 

[Robertb]

I know with the 996 it went suddenly from 1-2 yrs/20k miles in 2004 and I can't imagine that helped with bore score etc.

My Merc demands a service every year.

For what an oil change costs in the scheme of things I would do my 911 service annually regardless of the official interval, though I dare say modern high quality synthetic oil can handle more.

It's interesting that BMW M cars still use (or at least did til recently) special running in oil that needed to be changed at 1250 miles.

 

[Zingari]

Modern oils have moved on since the days of 20/50 mineral only, as have engines.

Most manufacturers know what they're doing and at least Porsche have the sense to recommend 2yr service intervals unlike the annual schedule some follow and don't need to. That said OPC pricing gives you 2 x annual service costs of other manufacturers :roll:

My Audi A2 when on variable servicing was allowed to go 2yrs/30,000 miles without needing a service - and that's a design that came out in 2000.

 

[911Time]

Modern synthetic oils are very good BUT on the DFI engines (997.2 onwards), I think an annual oil change is better, if you're interested in long-term reliability.

 

[Luddite]

I too go with the idea that Modern oils and engineering have altered expectations considerably.. though I can remember a time in the early 70`s when Duckhams Q reps visited the race tracks, a time when we changed oil regularly and some ran on Castrol R which had an aroma like no other..(-: The reps persuaded some with free samples of their green gloop, and in time "R" all but disappeared other than on special vintage machinery, and those who switched to the more modern oils did indeed find advantage in that for a start it was a simpler task to keep their engines clean.. (-:

It seems oil technology does not stand still and while there can be mechanical issues with older Porsches, I think that Porsche would perhaps think to make use of the best oil possible to ensure the reliability of their rather expensive engines when new and still under guarantee, perhaps more so when they are prepared to extend that guarantee over quite some period of time..?

I suspect that which Baz typed recently relative to the variables in relation to use and abuse that might be expected during the life of a "sports car" seems likely to differ to that of the average family barge, and in the worst cases I no matter what grade of oil might be used or how often it is changed, it seems possible that the outcomes may still be less than ideal.



PostPosted: Wed Apr 27, 2022 12:37 pm Post subject: Reply with quote
I response to the request for an estimate of anticipated reliability - it is a very difficult question to answer.

This is because of two factors few have any control over.

(1) How the car was driven and cared for by previous owners.

(2) The variability of quality in the weaker areas of the original design.

(1) Issues like - how much torque was applied on acceleration and from what revs, what oils were used, what grades and how frequently changed, how much deceleration changing down through the gears (flexes the crank and wears main bearings and then big ends prematurely), replacement coolant, pumps, radiators, pipework avoiding any overheating, ambient conditions, warm-up regime etc.

(2) Unfortunately these were a budget design (that is why the Turbos and GT3's cost so much more) and in my view did an fantastic job for the prices we have enjoyed since. However it does mean some areas of the design were compromised for long life compared to life expectancy of previous Porsche designs and this influences the quality of components fitted and the machining tolerances used during manufacture.

This means a variability in (for example) quality of piston coating adherence, distribution of silicon within the Lokasil matrix, clearances, age related stress relieving distortion and some parts not really fit for purpose (like the chain tensioners etc).

Put together is means a car with excellent machining tolerance build up, good silicon Lokasil distribution, top quality piston coating bonding, warmed up correctly, driven without high torque at low revs, in moderate climates, not stored for too long between running, and maintained properly (by ALL previous garages) and with thicker oils (as the engine wears) driven spiritedly but not tracked (by ALL previous owners) - might last 150,000 miles or even more driven very gently.

The same car driven as they should be (fast) should still be running at 80 to 100K but if stripped will have the start of piston coating loss, big ends worn below the white metal coating, and if left too long will eventually cost a lot more to rebuild.

Similarly a poor car (poor tolerance build up, coating, Lokasil etc) driven without good care, poorly maintained and with infrequent attention that overheated when the coolant pump failed etc - might need fixing around 50 to 60K.

Most cars are somewhere in the middle - good overall quality, reasonable maintenance, average driving - should last Ok to 100 to 120K (but might not).

Now the cars are aging there seem three main categories of owners - (a) retired always wanted one (low mileage careful driving, good maintenance etc) that keeps them going much longer and (b) younger or middle aged - proper maintenance and spirited driving combined - should last well and (c) not many in this category but - can afford a rough or cheaper one, track it, drive fast, can't wait for a warming up period before thrashing it - destined for early failure.

Then there is "ALEX" a rare category and engineer - understands quality maintenance - loves his car - very well looked after and should intercept any issues before they become too expensive.

I think the important consideration is NOT what difference it makes to re-sale values but what difference it makes to longevity - because engines rebuilt on the cheap seem to soon fail afterwards but engines rebuilt by specialists that have design and manufacturing capability (as we do) and who change the things that are weaknesses) like our improved cylinders, big ends, coolant flow and who change some of the technical specifications to the ones that were more reliable when part of the more expensive versions (like closing the deck with Nikasil plated aluminium cylinders as on GT3's and Turbos for example) - and improve the IMS bearing specification (which we also do) - result in a better specification than the original engine was new!

Meanwhile our capacity conversion improve performance as well.

But it is very rare for anyone to be able to buy an engine damaged car and get a reliable rebuild and end up making an immediate profit from it and so that is why I maintain that the influence of re-sale value after a Hartech rebuild is not really the issue - but the reliability and performance that can be expected for years afterwards and "SOME" increase in re-sale values.

Sorry it is a very difficult subject to be short and sweet about! and at the end it is still a gamble but they are still cheap cars with brilliant styling and performance and as long as that gamble is accepted at least there is a way to get failures repaired that are more reliable than others and probably better than the original.

I hope this helped.

Baz
_________________
Click here for the Hartech

You can trust us to "CARE FOR YOUR PORSCHE"
www.hartech.org

 

[911Time]

Considering the 997.2 (and 991.1) specifically: Although the basic design of the boxer engine remains, the engineering Porsche have used for their flat-six power plants, has changed significantly over the years and although I'm a fan of Porsche engineering generally, it's a fact that they don't always get it right - IMS, RMS, bore scoring, to name but a few.

Unlike the previous M96/97 engines, the 9A1 engines in the 997.2 and 991.1 have no IMS (cams use chain drive, directly from the crank) and the newer engine uses Alusil bore finishing, rather than the Lokasil (which suffered problems with bore scoring in the previous engine) but the differential expansion rates of the cylinder/piston are still a factor and adequate lubrication, with good quality oil needs to be a given.

One of the major changes in the 9A1, was the move to DFI and like a myriad of other detail changes, Porsche's main intention was to reduce emissions. Most vehicles now run DFI of one sort or another, or dual-injection (via indirect Port and Direct to cylinder), a host of problems have occurred across many mfrs as a result and one such is the potential for the directly injected fuel spray, to result in dilution of the oil. This is especially so when the engine is cold and the DME is running its rich Cold-Start program.

Unlike traditional port injection, DFI has little time to atomise the fuel, especially if an engine is running at high RPMs, so if the driver gets in and canes it from cold, without an adequate warm-up cycle, there's a good chance a lot of this fuel will fail to combust and simply wash down the cylinder walls, removing the oil film and diluting the oil in the process.

Add to this the effects of differential expansion between the cylinder bore and piston and differences in ovality between the bottom and top of the bore (caused over successive heat cycles) and potentially you have a perfect storm.

Why didn't Porsche anticipate this, you might ask? Well, why didn't Audi forsee the problems with the FSI engine/valve coking issue, or any other mfr for that matter? The truth is that manufacturers can test their cars under a wide variety of circumstances for thousands of miles and in so doing, arrive at a recommended service interval but it's totally impractical for them to simulate every possible driving scenario, over tens of thousands of miles and repeated cold/hot/cold usage.

Under the circumstances above, it's possible that the oil in a 997.2/991.1 could become diluted and lose its protective properties, long before the 20,000 mile service interval, whilst the expansion rate/ovality issues might combine to sow the seeds of problems, further down the line.

Therefore, if an owner of a DFI car intends to keep it for a long time (or has any conscience about future owners), it seems sensible to change the oil annually, or at say 5-10,000 miles (depending on use): Regular short journeys (or track use) at the lower end and longer journeys at the upper end AND warm-up the oil to operating temperature (c110 Deg C) before giving it the beans.

There have already been reported failures of the 9A1 engine from engine specialists in the UK/Europe and whilst the source of the issues are subtly different than those of the M96 and are even more likely to be limited, as they are influenced to a greater extent by owner usage and driving style, they also appear to be gradual and cumulative, rather than immediate & catastrophic.

Whilst you can check for over-revs, it's largely impossible to know exactly how a previous owner might have driven the car but whenever the car is purchased and at however many miles, a good maintenance routine can help mitigate future problems.

As much of what I've mentioned, has been reported elsewhere and commented on by people far more in touch with the developing picture of these issues than myself, there seems good justification to ignore Porsche's recommended 20,000 mile/2 year interval and change the oil at least annually. Coupled with a sensible warm-up routine, it's a small price to pay, for added peace of mind.

 

[Moko]

On a similar note how often should spark plugs be changed?

I think the book says every 4 years but for me that would probably be 20k as it's a weekend car averaging 5k per year. Most modern manufacture's recommended a spark plug change around 100k and some as low as 60k so does my 997.2 really need new spark plugs every 20k?

 

[911Time]

On a similar note how often should spark plugs be changed?

I think the book says every 4 years but for me that would probably be 20k as it's a weekend car averaging 5k per year. Most modern manufacture's recommended a spark plug change around 100k and some as low as 60k so does my 997.2 really need new spark plugs every 20k?

The recommendation is 4 years or 60k.

Most vehicles aren't driven like a 911, so whilst longer plug changes of 100k might be feasible elsewhere, it doesn't really make sense on a 911.

Plus for all the reasons I've just mentioned, a good fat spark will help to ignite as much fuel as possible, so yes I would stick with every 4 years for plugs, even if that's only 20k miles.

 

[Luddite]

Sorry Mark, (AKA 911 Time) I must have been typing up my ramble while you posted your thinking re DFI and suggestion that annual changes might be more beneficial... That you go into some detail as to why, who could argue with your thinking/logic.. ? Not I for sure.

The next question for those who keep their cars off the road all Winter, would seem to be.. When is it best to change the oil.. at the end of the season, to have fresh oil in it as it slumbers in the garage, or wait till the salt has gone to have fresh oil for the start of the new season... Hmm..?

There are those who think to have fresh oil with no contaminants lying in the engine during storage seems a better option..?

I wonder if it is just a case of splitting hairs as to when it might be best to change... :?:

 

[911Time]

The next question for those who keep their cars off the road all Winter, would seem to be.. When is it best to change the oil.. at the end of the season, to have fresh oil in it as it slumbers in the garage, or wait till the salt has gone to have fresh oil for the start of the new season... Hmm..?

There are those who think to have fresh oil with no contaminants lying in the engine during storage seems a better option..?

I wonder if it is just a case of splitting hairs as to when it might be best to change... :?:

Just speaking personally, I'm in the 'change it before lay-up' camp: Given the corrosive nature of the byproducts of combustion (particularly if the ratio of vehicle usage is biased towards shorter operation, rather than full warm-up, with a longer overall heat cycle), it follows that having fresh oil in the engine over winter makes sense.

The car is then ready for use at the start of the new season.

 

[Magic919]

The worry with the spark plugs is they might prove hard to remove.

Oil-wise, I think the interval is ok. Having added about 40-50k miles to two 997.2, I don't think the oil change interval is a factor.

 

[911Time]

The worry with the spark plugs is they might prove hard to remove.

Oil-wise, I think the interval is ok. Having added about 40-50k miles to two 997.2, I don't think the oil change interval is a factor.

Agreed, plugs can be a beggar to remove if in situ too long.

I believe the engine's susceptibility to the issues mentioned, is dependent on the combination of factors outlined plus a few less important ones, so whilst one owner might not experience any problems at all during their ownership and cover maybe 50-100k miles, someone else might 'inherit' a car that's been driven or cared for differently and see issues down the line.

Just out of interest, how often did you change the oil in your own cars? Twice in 40-50k, or more often and were your typical journeys long distance, or local stop/start?

 

[Magic919]

Oil changes were every other year. C2S was over about 7 years and the C4S is just over 9 years ownership now.

Hard to generalise about the use, but mostly shorter trips as a DD, with the cars alternating for the Euro hols 2-2.5k twice a year plus longer U.K. trips from time to time.

 

[Moko]

For my work/lease cars covering 20k per year as required normally once in a three year ownership.

For my 996 covering 5k per year once a year and I'll probably stick to changing the oil myself for my 997.2 every year as well.

As to driving my car does a few short trips in London but more long distance ones to West Country etc so it gets driven reasonably hard.

I saw an ad for a rare Porsche the other day that had covered less than 14K in its 20 plus life but had 26 dealership service stamps, just seems ridiculous amount of work on a car thats done less than the average car does per year.