Reading this could make you hypervigilant about your sports car maintenance...
...especially if you own a Porsche 911
I recently had a 2017 Porsche 911 Turbo S in for service (991.2 Generation), and it had only clocked 11,000 miles on the odometer but already had a complaint of a chattering from the driveline while taking tight radius turns (and no, it wasn’t the control arms binding and unloading). Knowing that this vehicle owner is a proper sportscar enjoyer, I knew that this car has had a couple track days and is driven how the engineers intended…so I looked at the recommended maintenance from Porsche AG. Scheduled maintenance always amuses me because if you quizzed every vehicle owner about the type of usage their car received, you would probably just advise them to change all of the fluids at the earliest recommended mileage to play it safe. There are some Porsche owners who just use it for a Sunday parade lap around town with the top down and they may not need as frequent of service as one that seeks enjoyment by ripping up the Kancamagus Highway. When you see an SUV with a trailer hitch, 3rd row seating, and all sorts of stickers from ski resorts on the back window, you know that thing has had some significant usage and should have its fluids changed a little early. The same mantra applies to sports cars. If you can make an accurate assumption or any sort of confirmation that it has experienced some hard usage, you should recommend that the fluids are changed early and the condition is evaluated. If it can be justified, make the recommendation.
Even if the manufacturer says that driveline fluids should first be changed at 18,000…24,000…30,000 miles, if you look up the fluid capacity for one of the components and how expensive that component is, you may decide to recommend it earlier. This client doesn’t require any convincing on any recommendation ever. Once the words are out of my mouth, the next thing heard from his is “when can it be done? let’s arrange to have it detailed after the work is done”. We decided to change the spark plugs, engine air cleaner, cabin filters, every main fluid in the vehicle (PDK hydraulic oil, PDK gearbox oil, engine oil, electromagnetic clutch oil for front differential coupler, front differential gear oil, engine coolant, and brake fluid) as well as a few other small maintenance items.
I’m not going to explain any specific steps and specifications of these general service procedures or reproduce any documents from Porsche AG, but I will explain some things that are not common knowledge and have only been learned from my recent experiences servicing these cars.
In order to replace spark plugs in this engine, Porsche recommends dropping the engine down which requires disconnecting a bunch of hoses and connections and it is a sizable procedure compared to other cars. To clarify, you don’t need to remove the engine, they just want you to disconnect the engine carrier from the mounts and lower it. The book warranty labor time is about 3-5x what it would be for most common passenger cars, so that means that customer-pay labor time is hit with an additional calculation or “labor matrix”. The involvement of this job is now somewhat common knowledge, there are people who have created YouTube videos on replacing spark plugs on the 991.2 car so that information is online. The torque specs and individual repair documents are not, and I will not reproduce those for anyone. Porsche AG watermarks all repair documents with your username and date as well as some other coding so if the document is leaked somewhere, they know who did it.
There are times when you are assembling a recommendation list (and repair estimates) that you realize that multiple birds can be hit with the same stone if you recommend 3 or 4 maintenance items to be done at the same time. It may be because a step involved in another procedure actually overlaps and makes the main procedure easier. If it would be wise to do those other jobs anyway and you can justify recommending them, then you absolutely should. This is part of flat-rate life, and it helps in becoming an efficient technician. Encouraging customers to be more vigilant about maintenance is justifiable.
In this particular car, I recommended replacing the engine air cleaner, and that involves removing the rear bumper cover which has a decent number of preceding steps. If you already have the bumper cover off, it’s about the same amount of work to get access to the spark plugs if you remove the intercooler assemblies from both sides and remove some heat shields compared to disconnecting the engine mounts and lowering the engine to get access that way. The plus side to removing the intercoolers is that you can flip them upside down to clean all of the little leaves and debris out of the ducting, which you wouldn’t do if you were just lowering the engine. At just 11,000 miles, this car already had some significant leaves and maple seed “helicopter” pods trapped on the intercooler. Getting access to the spark plugs from there involved disconnecting a bracket on one of the turbochargers to sneak an ignition coil out, but it really wasn’t terrible. I could see how some people could get frustrated if they unknowingly underquoted the job though.
Moving onto the driveline fluids, there were no real surprises to the procedures there, but I briefly mentioned earlier how you would be inclined to want to change the fluids earlier than the manufacturer recommends if you knew how expensive the components were and how much (how little) fluid is in each one. In Porsche’s defense, the front differential does have a fluid cooler that reduces the temperature BUT it doesn’t use much gear oil for the differential itself and it REALLY doesn’t use much in the electromagnetic clutch coupling system on the differential input. I won’t say exactly how much fluid goes into each one, but I will say that if it was beer and you chugged that same volume, you would be merely buzzed. It’s good to make sure that you have the correct fluids from the dealer for the procedure before draining them, because there’s nothing worse than dumping the oil and finding out that it’s some special-order shit from Mother Russia! and finding out their chemical plant got bombed last week and there’s none left on earth or something. I actually had to download the complete parts catalog for this vehicle and order the differential fluids via the part numbers because the wholesale dealer parts clerk wasn’t sure which ones to get. I honestly don’t think that wholesale parts people deal with many inquiries for 911 Turbo S parts from 3rd Party repair shops, the parts people for their own Service Departments are familiar with less common cars because they are brought to them for service.
I stood there looking at the two drain plugs knowing that I won’t need a very large paint cup in order to capture the escaping oil for visual inspection nor will I have to stand there for very long. Both drain plugs had magnetic inserts which had collected a good amount of fine metallic particles and is normal, the fluids drained were opaque and very dark in comparison to how transparent the new fluids were. I like to use Genuine dealer fluids for these comparisons not just because I know they will be proper/correct but because there are some instances where a fluid will be drained, and it has a pigment that makes it semitransparent. In those cases, one would believe that it is dark and contaminated/worn but when it is compared to the new fluid out of the bottle, they don’t look too far off from each other. That was not the case with this vehicle, these fluids were very dark in comparison to the new stuff. Considering the 5-figure price tag of replacing a front differential in one of these cars, a few hundred bucks to change the oils every 10,000 miles should be cheap insurance. The simple fact that the electromagnetic clutch only holds a very small amount of oil means that it becomes contaminated with clutch material very quickly. The electromagnetic clutch operates similarly to a Honda CRV rear differential coupling, it does not operate the same way as a Haldex unit and does not contain a fluid filter or hydraulic pump system.
The PDK hydraulic unit and gear set oils are very straightforward, there are some specific instructions in the repair procedure as well as some physical & software tools for doing the job that make it something only a trained technician should be doing. There are certainly some videos of drunk Brits on YouTube doing their own PDK fluid services, but I absolutely do not recommend “eyeballing” everything the way that they were. I could also see how someone could easily fuck themselves over by pulling the drain plug out of the gear set side of the transmission and then realizing that they don’t have a tool that can get access to remove the fill plug. ALWAYS remove the fill plug first, because it’s a giant kick in the balls if you remove a drain plug and find out that you can’t remove the fill plug without destroying it.
I think the driveline fluids should all be changed at 10,000-12,000 miles. Mismatched/worn tires front-rear I’m sure contributes to that electromagnetic clutch fluid wear, so encouraging good habits with tire replacement and not allowing them to develop significant disparity in wear will prevent rapid component wear. The PDK hydraulic oil and gear set oil both were dark and contaminated with wear material. With our BMW M4 GT4 (which is a factory-built race car), the technical literature doesn’t really have a super frequent fluid change interval for the DCT oil, but they recommend replacing the Dual Clutch Pack at 15,000km (9,000 miles) and the entire DCT assembly just 15,000km after that. So, they’re essentially saying that a vehicle rated at around 425hp needs to have the entire transmission replaced after 18,000 miles of track driving. We change all driveline fluids in the car after every race weekend, which is less than 1,000 miles. The fluid is definitely noticeably different in color from wear after one weekend of use, so I believe changing oils every 10,000 miles in a car that makes close to 600hp is reasonable and smart if you want components to last.
The 991.X also has a water pump that has a vacuum actuated shroud that can block off coolant flow to/from the impeller. This is a common method of controlling engine coolant flow and therefore reducing mechanical drag from the accessory drive system which affects fuel economy. VW/Audi/Porsche have been doing this for quite some time now with many models. This vacuum actuated shutter system is prone to causing engine coolant to escape into the vacuum lines when the water pump fails, and that coolant crystallizes and causes failures to other unrelated vacuum solenoids that are all tied into that same system. Changing the engine coolant regularly reduces wear on the water pump bearing and prolongs the life of it. Replacing the water pump is also not a total walk in the park on the 991.X as the entire engine carrier plate has to be unbolted which involves removing the rear bumper cover and the entire exhaust system from the turbochargers which is substantial. If you put it all together and don’t realize that coolant has damaged the vacuum solenoids, then you may find that the bumper cover has to get removed again in order to replace those solenoids and vacuum lines. The technician recommending fluid services that only cost a few hundred bucks is actually trying to prevent the customer from spending a few thousand to replace the water pump or over $10,000 to replace a driveline component.
The photo below shows another 991.2 car (911 Targa 4S) that needed a water pump, it involved a decent amount of disassembly for access, you can also see the leaves and debris that were trapped in the intercoolers as well as the number of vacuum lines and solenoids that are clipped to the intake piping behind the bumper cover:
I don’t share this information because I want to give away trade secrets or show people how to do the job of a technician. I think that vehicle owners deserve to know the firsthand reality of what goes into repairing their car and how frequently they should be servicing it. If you leave people in the dark, they won’t understand where their money is spent and why it is necessary to service it a certain way to promote longevity. In general, Porsche owners are vigilant about their vehicle maintenance and understand the benefits of taking optimal care of it to ensure flawless operation and continued enjoyment. I believe in Right To Repair because manufacturers should not legally be allowed to hold a monopoly on the repair of vehicles, but I also agree with Porsche AG’s stance that these aren’t ordinary vehicles and they require specialized attention from qualified personnel. Leaking Porsche’s step-by-step repair instructions and reproducing official documents for public use undermines their effort to prevent unqualified parties from making repairs and that jeopardizes the safety and quality of repair. There are gray areas in the entire discussion and I’ve stopped believing thinking of it as a black and white matter.