BucketList

OK then!! It seems the experts agree I am idling too long. I just didn't want to seize her. I will take your advice.

I am still on the fence about what oil to use though. My Porsche mechanic says M1 is junk and swears by Castrol. I know Castrol is good oil, but in my experience so is Mobile 1. My test rig is a 2006 Acura TSX with 220K miles on it and nice loose rings. It won't start using good oil until after about 2k miles, that's my indicator. Oh and I don't want to start an oil thread... just talking...

Vincent713

I have a question regarding the warm up procedure. Here's my scenario, I work from home and on a daily base I need to drive to the post office, bank, store etc all within 5 mile radius. Would it be bad for a 997.1 if I was to dally it according to my scenario?

C4SDayton

Short frequent trips are "bad" for every car with an ICE for plenty of reasons. Are they really worse for a Porsche? Worse than some and better than others I assume. It is still a car. More preventive service is needed like more frequent fluid changes and filter change and Porsche service is more than Honda. A majority of people seem to use their 997s more sparingly than as a DD. Since you won't be warming up car doing these trips, you should drive easy on all these trips. I don't really care what your other car or cars is/are, money considerations aside, I'd rather drive my 997 to the post office than a sedan or SUV if space isn't an issue.

Claydus

Has there been any correlation of engine failures and the type of transmission? More manuals vs automatics?

Hula

It would be bad if that's all you did. Take it out every couple of weeks for a longer drive to get things up to temperature. Then rev it out a bit. It will get rid of any moisture the tends to accumulate.

Petza914

Ideally, you want to get the oil to full operating temperature to burn off the condensation that forms in it during the warm up process. Take the long way to the first stop and use the drive through at the ones you can to prevent shutting off and restarting the car when possible.

Vincent713

Thank you gentlemen for the replies and feedback. Those are some great advice and I shall follow.

bazhart

WARMING UP ISSUES WITH THE 9A1 GEN 2 ENGINE.



This subject of warm up procedures relating to the potential for cold seizures (like many others on this type of forum) is the subject of a classic mistake that many clever, capable and well intentioned contributors frequently make by becoming too focused on what they assume is the salient issue and then launching into perfectly well thought out and reported facts, figures, historical experiences and advice relating to what they think are the contributory factors – that are very convincing (and usually accurate and correct in their reporting) but actually are not related to the actual cause of the problem at all and therefore miss the point.



Cold seizures are the result of the piston becoming larger in diameter than the cylinder bore they run in – in specific places - so that the pressure from the piston face on the cylinder wall overcomes the ability of the oil to keep the moving parts separated and the resulting heat generated leads to micro-welding and classic seizures.



Although both the coolant and oil temperatures influence the temperature of the metal forming those interactive areas it is the temperature of the metallic parts (and the rate at which they heat up) that directly influences the size they expand to and not the temperature that the coolant or oil has reached over delta time.



From cold - the heat gradient is highest at the top of the cylinder (where combustion is hottest and the head and top of the cylinders experience the temperature rise first).



Lower down the cylinder, the heat from combustion has reduced (as the expansion of gas reduces temperatures proportionally) and the exhaust and exhaust pipes are the furthest away – so the metal down there heats up more slowly than at the top of the cylinder.



Furthermore the very top of the piston (where the rings fit) is machined very much smaller than the cylinder bore (and is never going to expand enough to force radial interference) while just under the ring area the piston is tapered and is smaller than the biggest diameter (and closest to the cylinder wall) about half to two thirds down the piston measured under the rings.



This means that the part of the piston that is largest and the part of the cylinder that will expand the slowest will interfere (if they are going to) lower down the cylinder where cold seizures always occur and where almost all the evidence we have (and have seen or had reported from others) of Gen 2 engines – is located.



Although it is possible to make calculations for the thermal expansion of a free standing component (using the start and finish temperatures and the thermal coefficient of expansion) these calculations do not work if the material is constrained such that the cooler areas resist the expansion of the hotter areas.



This fact is the key to both understanding cold seizures and relating them to differences in the real world between the Porsche 944/968, the 911 M96/7 Gen 1 engines and the 911 9A1 Gen 2 engines - in which those constraining influences are very different.



Just dealing with thermal expansion from cold – and first looking at the 944/958 – the top of the cylinder is open deck and a free standing cylindrical tube that warms up quickly and is not constrained while the bottom has all the warming coolant reaching close to the cylinder base (deep coolant channels) and 100% of the coolant passing round the cylinders before flowing up to the heads. This makes the warm up and therefore the cold to hot thermal expansion rate relatively fast.



The Gen 1 M96/7 has both the top and the bottom of the cylinder free standing open deck and therefore although a smaller % of the coolant flows round the top of the block this actually enables it to heat up faster. So although the coolant only reaches the top areas (relying on the oil splash to warm the bottom of the cylinder) the bottom of the cylinder tube also warms up quickly from the heat being conducted through the oil film from the piston and the oil splash and spray tubes also because it is both a thin tube and un-restrained.



The Gen 2 9A1 engine is completely different and is closed deck at the top and bottom. This means that the whole of the cylinder block is homogeneously connected to the cylinders top and bottom and therefore the cylinder bore is constrained from the rate at which it can thermally expand by the temperature that the whole of the cylinder block has reached internally and externally - and not just the cylinder bore area, coolant or oil temperatures.



The top middle and bottom of the cylinder bore will therefore warm up more slowly and expand more slowly in the Gen 2 9A1 engine.



Measurements and comparisons of the rate of coolant and oil temperatures rises does not directly correlate to the expansion rate of the cylinders and out of these three different engine examples the Gen 2 9A1 will have by far the slowest lower cylinder expansion rate and lag well behind that of the oil temperature.



There are other external influencing factors as well. The 944/968 engine is located directly behind the radiator and the oil cooler is low down in the cylinder block and this results in more heat passing over or reaching the internal and outside of the cylinder block, allowing it to heat up and expand faster.



The Gen 1 and 2 engines have the radiators no where near the engine and the oil cooler on top – so the extremities of the cylinder blocks heat up much more slowly.



Now we must consider ambient differences. In freezing sub-zero conditions the engine is frozen from cold and even when it is running and heating up with both coolant and oil temperatures at their operating conditions – the outside of the engine casing is still cold and has freezing air is flowing over it – conducting heat away and slowing the rate that the whole block is heating up and with it the rate at which the internal cylinder is able to expand and this constrains the rate of lower cylinder expansion.



The outside of the Gen 2 cylinder block on both sides is homogeneously connected solidly to the lower cylinder bore by a large and solid piece of aluminium that forms the area that the main bearings are fitted and as such the temperature of the outside of that casting restricts (or constrains) the expansion rate of the lower cylinder in exactly the circumferential position that the piston ovality is at its biggest (in the thrust direction) and therefore does influence the rate at which the clearance between the piston and the cylinder changes as the engine warms up. In contrast not only is the lower cylinder tube free standing in an M96/7 Gen 1 engine but the crankcase/block has a huge hole in its centre where a completely separate casting cassette that holds the main bearings and crankshaft – fits into – and therefore although there is a joint face between them the effect of any constraint is far reduced.



So despite all the completely correct analysis of coolant and oil temperature rises with time (gradients), graphs and comment and the combined advice based on historical experiences of different engines etc (which is almost certainly right) unless there is a broader understanding of a wider range of issues that result from looking at all contributory factors first in much more detail (and being more familiar with the engine construction and how it all works) and identifying the most important ones (and understanding exactly what is going on) it is easy to get deflected from the actual cause and provide convincing data that seems to support an argument that actually has little or nothing to do with the cause.



All the above means that the 9A1 Gen 2 engine lower cylinder bore will expand at a very much slower rate than a comparison with a 944/968 or M96/7 Gen 1 engine and therefore could be more susceptible to cold seizures – absolutely!



We may differ in agreeing what those temperatures are during the warm up phase and therefore how much the thermal expansion is under constrained conditions but it is in our experience more than 0.001” (0.025mm). This is very close to the standard piston to bore clearance of the Gen 2 engine



Now – pistons do deflect and if the oil quality is good can run with increased pressure between the piston and the cylinder bore for short periods when the clearance is tight by slightly deflecting the piston skirt (where it is biggest) inwards but does result in higher oil film temperatures between the piston and the cylinder bore and therefore poorer lubricity. If the revs are high the piston face friction is higher and if the throttle is being used fully open through to higher revs the resulting temperature between the piston and cylinder is higher – therefore it is more important in the Gen 2 engine to allow longer for the whole cylinder block to heat up and expand without constraining the lower cylinder bore until the clearances will work effectively.



Furthermore, because the Gen 2 has reverted to the 944/968 Alusil hypereutectic bore system - the hard iron piston coatings that were available (and are considered essential by some experts) are no longer in use and in our experience the new metallic coating is good but not quite as durable and we feel this might explain why the Gen 2 piston has a profile that spreads the load over a larger area of the piston face. But although this would help the piston to bore wear to last longer – it also means that with tight piston clearances anyway – any delay in lower cylinder expansion would be more likely to result in a cold seizure.



Although my example above used the freezing ambient conditions to try and demonstrate the issues better even a start temperature of say 15 or 20 degrees centigrade has minimal influence on those overall expansion rates between cold and fully hot all over cylinder block temperatures – it just makes incidences a little more likely (and therefore statistically more reported) the colder the weather is.



So before all the arguments begin – if the above is right – then the evidence would be that we would see more cold seizures is the winter and resulting from fast driving off from cold – and this is so far 100% of the feedback we have received.



But there is another additional factor we have also measured and proven to afflict 100% of the engines we have seen – that the bottom of some cylinders have slightly closed in smaller through age related casting stress relief than the size they were from new and during their lifespan.



This means that although the above explanation is valid (that the Gen 2 would be more vulnerable to cold seizures) it may well be that IF the cylinders remained at the designed bore size – they would survive even an impatient warm up in cold conditions. But the cylinders we have measured had shrunk by around half a thousandth of an inch (0.0005” or 0.0127mm) and this definitely would result in the cold clearances being too tight if the engine was driven under high power too soon. luckily most drivers only drive at racing speeds never or rarely so mist owners only drive at similar speeds to other saloon car drivers and therefore actually with relatively low heat generated in these engine internals - and actually enable things to warm up with suitable clearances anyway. So – as long as the car is not driven under high loads from cold – the temperature of the piston crown and faces (and the resulting expansion) is considerably reduced – so although the cylinder bore may be slow to expand it probably would not result in too tight a clearance.



Similarly as long as the revs are not too high then the friction between the piston face and the cylinder bore will be less (and so will the resulting piston temperature and expansion).



However somewhat contradictorily - driving too slow will delay the whole warm up to running temperatures and reduce clearances.



This means that in our opinion the best thing to do is to drive off slowly from cold without using too much throttle or maximum revs but probably driving at a speed and acceleration rate that most saloon cars drive at on speed restricted public roads – keeping up with the flow but resisting the temptation to deliver the performance that we buy these cars for – until the whole engine is up to designed temperatures and the clearances are sufficient.



Sometimes the most simple explanations and the publics general experiences and advice - are right – and this happens to be the case here.



Alusil (like all hypereutectic cylinders) will eventually (after very high mileages) wear the bore surface smoother and reduce the effectiveness of the oil film and so it is possible that (just like the 944/978) after many years a cylinder may score (or less likely - seize) as a result but I would expect this failure to be insignificant statistically.



Some contradictory explanations and advice have appeared from other respected sources. It would have helped us determine the proportion of failures caused by cold seizures to see pictures of the inside of the cylinders affected - although in some cases the contributors have refused to provide information to support or go against this explanation while neither they nor another have yet measured a seized Gen 2 block or piston and therefore could not possible have been led to this type of investigation and conclusion (and probably would have agreed with it if they had).



It must also be clear to less naïve readers that there could be a business benefit from not contributing information that might avoid or delay engine failures.



Whether alternative advice or explanations are innocently reached and provided or not - sometimes (in fact usually) the most simple explanations and the publics general experiences and advice - are right – and this happens to be the case here.



However we never allow commercial influences to override genuine advice and will continue trying to explain the causes in such a way that the general pubic can follow and believe in. It is not easy or quick and hence this regrettably long but I hope completely convincing study will help some owners to keep their engines running reliably throughout their ownership.


By luck most drivers will not set off from cold too fast anyway and allow these excellent engines to last as expected for typically huge mileages.


Baz

Charles Navarro

We did a little test last week. For those who do use the Ceratec, we mixed it with an oil that had no moly and no boron as to see how the additive blends and if the samples would hold the Ceratec in suspension:

Oil Molybdenum (ppm)

Base oil 0

Base oil + Ceratec 345


Oil Boron (ppm)

Base oil 0

Base oil + Ceratec 261

This puts the Moly levels in line with DI40's 300 ppm. Boron is another anti-wear additive that is used to boost the AW films in lower ZDDP oils, so adding boron to a low or mid-SAPS oil would also help reduce wear.

Has anyone on this forum done used oil analysis on their oil both before and after running Ceratec?

wjk_glynn

Hi Baz,

I’ve always followed that procedure on my .2 for ~15 minutes (approx 10-20 miles where I live), until the oil temperature comes ‘off the peg’.

Which is 150F / 65C on US models.

In your opinion is that sufficient, or would you allow longer / higher-temp ?

Cheers & thanks.

Karl.

bazhart

15 minutes should be OK if the shrinkage we measured stops where we measured it. There is no way of knowing anything else until different evidence does or does not arrive and anyway some cylinder blocks we have checked have no shrinkage so it might be random or even cured in later models.

It could also be that the stretching caused through heat cycles changes the cold set position.

Please do not hold me responsible if this best advice does not apply to you or your car but I very much doubt you will experience any problems,

Baz

wjk_glynn

Thanks Baz,

And I totally acknowledge allowing 15 mins is just an opinion given the constraints of the available empirical data (as measured/observed by yourself, etc.).



Karl.

Fahrer

You make too many assumptions. This type of thinking is what contributes to the myth that garage queens are doomed to an early death. My 997 is a garage queen an it is not a daily driver. I drive it only on good weather days and I always warm it up appropriately ( drive away with light throttle and and less than 3K rpms until the oil reaches an indicated 200F). I always drive Porsche at least 45 minutes but generally 1.5 hours at a time. It exists in my garage purely for my driving pleasure. I drive my DD to places like the post office because other drivers are often careless.

Actually, I break my cars in and warm all of my cars up the same way and I never had an oil consumption issue with any of them.. even the 911.

Balr14

What you said agrees with what C4SDayton said, a car doesn't get warmed up using it for short errands. You don't use yours for short errands.

Fahrer

I should add that some folks feel that all you need to do is bring the oil temp up to 212F ( boiling point of water at sea level) to remove all of the water from the crankcase. This is not the case. Actually if these engines only got up to an oil temp of 160F and were run for and hour, they would have less water in the crankcase than an engine that has reaches 212F and has been shut down after another 5 minutes. It takes time. When you bring a pot of water to a boil on the stove you still have a pot full of water. The pot will eventually dry out whether at 212F or 160F.