I seek optimal solution to tackle this issue. First idea was external oil cooler but there is lack of decent commercial products. After usual disappointment I fired up my super computer with SolidWorks and started to design my own oil cooler. Then, I realise why I do everything so complicated.
Next step was testing various engine oils. Extensive research of automotive forums where you rarely find anything useful other than eExperts fighting over who has truth – if you want something right you have to do it yourself. Nothing beats trial error experiments where you become intimatelly familiar with all issues and dynamics involved in process.
I started with engine oil lab analysis. I didn’t find suitable service in Europe and started to cooperate with guys from Blackstone Labs in USA.
- first report – 158k km right after purchase. I have no idea what previous owner did with this car but engine oil analysis is catastrophe. Based on high amount of fuel in oil, it was driven short trips only with excessive amount of DPF regeneration and most of them never finished because it took me a half year of excessive EGT temps to burn out DPF. Excessive engine wear. German services usually use Shell 5W-30 oils. Recommended replacement interval 5000km.
- 160,805km – my first kilometres and debugging car issues. I wanted to see what is going on with new used car. Liqui Moly TopTec 4100 5W-40. I never been a fan of 5W-30, they rarely work in cars with 100k+ km on ODO.
- 163,636km – better safe than sorry. First report didn’t look very well and I was carefully observing my car. Same oil as previous report, just more kilometres on it.
- 176,678km – 8,037km if you don’t try both side of extreme you never know the difference. Q8 Formula Excel 5W-40 from drum. Cheapest but most deadly option in third world countries. Czech dealers/sellers are like a box of chocolate…you never know what you get. ECU remap art 171k km. Wear lower than LiquiMoly but viscosity at high temps still rubbish.
- 185,511km – 8,833km after ECU remap it has never been same. They say, fuel economy improves…if you can drive as before. But who drives as family lost on shopping trip with 170HP, right? I used standard VAG recommended oil from Shell but 5W-40…what my friend had in garage. I drove short trips combined with full load/flat out on alpine roads. DPF regen caused excessive level of fuel in oil, wear level and poor viscosity same as other oils. There is little difference mong most oils I guess.
- 193,032km – 7,521km same oil as in previous report. Little difference. Less fuel in oil most likely no shirt trips.
- 201,172km – 8,140km I always wanted to try legendary Motul 300V used by Prodrive for Subaru Impreza WRC. It has got great thermal capacity and thermal shock recovery…but price is steep especially when you drive 20-30k km annually. I’ve heard great stories about Mobil One oils. I’ve found similar product as Motul 300V but suprisingly cheap. Too good to be true. Who cares, only experiments and results speak truth. Mobil 1 Peak Life 5W-50 was surprise for me. Dreams come true if you will. Strong TBN and finally viscosity as promissed by manufacturer.
- 204,667km – 11,635km still same oil as in previous report. I wanted to push it more and see what happen. Increased wear caused by some fun on German Autobahns…two hours at full load with average speed around 200km/h. EGT (exhaust gas temperature) constant at 800+ deg C, oil cooking at 110deg C…yet this oil refuses to die…even soot levels low !!! Service interval increased to 12k km and next time I push it even more. I wonder about hot summer time where comes most fun with cooking oil with 120deg C…oil temp where most oils fail.