skullbox15

I usually run 5W-40, but after Dr. Tasos suggestion I switched to 10W-60. I'm in Florida so I'm not worried about cold starts. I've noticed the temp seems to rise a little quicker. Has anyone else noticed this? Is the oil cooler less efficient with such thick oil?

Solo wing

Higher viscosity = less flow = more friction.

This is a good read:
https://www.opieoils.co.uk/t-car-eng...explained.aspx

Jasonoff

His suggestion for 60wt is for extreme hot climates which you are not in. Switch back to the 40wt before you destroy your engine if you have not already done significant damage.

ALFAitalia

No need to frighten the life out of the guy!.....its unlikely to have caused damage, especially if he does not thrash it from cold. Might be a different story if it was turbo charged!

skullbox15

It's 90-100F here in Florida. I'm used to the way I drive how the temps climb. It seems to be about 5 degrees warmer. Where I'd normally reach 225, it's now 230.

Diabolis

I usually run a 5W-40, but after Dr. Phil's suggestion I run a 70-30 mixture of organic shea butter and a proprietary jojoba and tumeric oil mix. After about 3 minutes of driving, the engine temperature went berserk and my engine started making a really loud ruckus. Has anyone else noticed this? Is the oil cooler less efficient with such special oil?

downhiller2010

I run 10w-60 as well and was recommended to do so by a very well respected AMG mechanic who has built a few m156 based race cars.

BLKROKT

Oil is unnecessary weight. Who needs it. I like just a few squirts of WD40 personally.

HLG600

There was also a comment thread in one of the M156 videos on YT where a person claiming to be a former powertrain engineer for AMG (involved in the M156 and M157) recommended the same. At the end of the day, it's piecemeal guidance.

I would treat Tasos as the most credible source due to his transparency and there are multiple times he recommends 5W-40 for most use cases. Florida is hot but not scorching like it is in the UAE where he is from.

If I lived in Palm Desert, CA where the climate is similar to his, maybe I'd try 10W-60.

The formula for these engines is pretty simple:

5W-40 if you are in a warmer climate / drive it in warmer seasons only.
0W-40 if your M156-equipped AMG sees winter duty.

There are multiple options in the above weights that give your engine the best protection possible.

Valvestud

Use this for MB approved weights:

Ludedude

I prefer the more environmentally responsible organic olive oil in a soy based, not plastic, sprayer.

Diabolis

Regardless of what Tasos says, a hot 60-weight oil is much too thick for the M156 if you want to provide proper lubrication and cooling even in hot climates (what you need is additional oil cooling capacity, NOT thicker oil). What weight oil do you think the AMG GT3 race teams run in the M159s when they race in Dubai and Bahrain (hint: it is not xW-60)?

Diabolis

This is first hand information from a top AMG mechanic for North America who spent a lot of time at Affalterbach, and is one of a number of technical support reps for the AMG Customer Racing programs for their GT3 and GT4 customer race cars. His explanation - directly from an AMG powertrain engineer (someone who actually is one, not someone posting things on YouTube) - is that the various journal bearing clearances at operating temperatures when all metals are fully expanded in the M156 (with the forged rods and crankshaft from the M159, which apparently expand at a slightly different rate than the cast ones... figure that one out) and of course the M159 optimally need about 10 cSt of oil viscosity. While thicker oil provides a higher load capacity (film strength), it decreases the oil flow rate and in turn increases the bearing temperatures which results in very premature failures.

The oil viscosity vs. temperature change is non-linear. At low temperatures, a 10C difference results in a massive viscosity change, however at operating temperatures (100C) a 10C increase in oil temperature only decreases the viscosity by 1-1.5 cSt. Thus, you'd need an oil that has a hot rated viscosity (at 100C) of about 12-13 cSt in order to keep the viscosity at ~10 cSt at ~120C which is where the M156/M159s operate. Oil shear over time (over thousands of miles) and dilution will also somewhat decrease the oil viscosity, but not nearly as much as temperature. Thus the stipulation that only 0W-40 and 5W-40 oils are used in an M156 and M159 engines and that on the C63 that some of us flog harder than others we need additional oil cooling capacity to keep the oil below 120C.

10W-60 oils have a 22-26 cSt viscosity at 100C, so even in Tasos' case in the UAE or wherever he is located, a 10W-60 is still going to be much too thick (~20-24 cSt) for this engine and will absolutely result in premature engine failures. The key is not to use thicker oil, but rather to keep the oil viscosity very near 10 cSt at the temperature the engine is operating at. All the AMG GT3s that are raced worldwide in various endurance series including the 24h Dubai race run a xW-40 oil.

HLG600

Good info and perspective, Diabolis. Thank you for sharing.

/Thread

skratch77

Ask that engineer why the m156 eats cams lifters and adjusters. Ask him what oil to use to get more than 15k miles out of the adjusters.

deadlyvt

😂

skullbox15

My main reason for trying said oil.

Solo wing

Well even if we assume that 10w-60 will in fact protect the camshafts and buckets, we do not know how thick it will be for the oil journals and bearings.
IMO I'd rather replace the camshafts + buckets over lower-end repair.
Once I used Liqui moly 10w-60 here in the summer and I live in the hottest place in the GCC. It poured down like honey compared to 5W-40.

Diabolis

All engines - in particular OHC flat tappet designs - eat cam lobes and lifters, just like they eat *everything* else. The M156 (with the updated lifters) / M159 are one of the most reliable power units, period. If you are wearing out your lifters in 15K miles, you are either using the wrong oil or you've molested the engine. The pre-2020 factory AMG GT3 racers run for 20,500km under RACE CONDITIONS before the engines need a refresh, with most of the wear occurring on the bottom end (and the 2020+ cars have better crank and rod oiling and are rated to go even longer between rebuilds). If you are managing to wear out the exact same cams and liters in mostly street driving in your C63, you're definitely doing something wrong.

Your specific experience notwithstanding, would you rather have to replace camshafts and lifters every ~100K miles, or have your engine seize at half that mileage when you spin a crank or rod bearing? Camshafts and lifters are wear and tear items. So are your brake pads and rotors... do you also whine about them wearing out?

hachiroku

this is not a junkyard BMW where the have to run 10w-60 because they designed their engines to explode after the warranty has ended by making their rod end bearings too tight. funny that they don't even care that the thicker weight causes issues with vanos.

literally you have absolutely no reason to run thicker than 5w-40 and will see higher temps because the oil isn't able to move quickly enough to pull the heat out of the engine. thicker weights also will suck power out of the engine.

if you are looking to do endurance racing, you may want to go to a single weight oil and preheat the oil prior to engine starting but going to a 60 weight...don't do it.

WolfpackC63

Our engines seem to run a bit hot. On an 85°F day running Tail of the Dragon I was topping 280°F oil temp.

I'm going to VIR for a two day HPDE in a few weeks. Should I still plan on running 5w40 oil?

Diabolis

It's not our engines that run hot per se... it is insufficient oil cooling capacity that makes them run that way.

Yes, I would definitely use a 5W-40. Thicker oil flows less readily and actually removes LESS heat from the engine (so the oil itself may be a few degrees cooler but the hot spots in the engine itself are even hotter). You will still overheat the oil without the 44O kit, Sven's cooler (@SRG_C63) or some other similar solution. 280F is way too high and awfully close to limp mode (only one of two degrees below... not sure what it is in Fahrenheit but it is right around there).

WolfpackC63

Thank you!

I mean honestly it blows my mind a bit. The C63 would "appear" to have sizeable heat exchangers from the factory. The oil cooler seems like a decent size to begin with, and 8 quarts is a lot of oil. Even just cruising down the interstate this engine runs hotter than the 2.0T in my GTI. I plan to just dabble on track with the C63 once or twice to see how much I enjoy it. Definitely not committing to a $3000 oil cooling upgrade package at this point. If temps get hot I'll just ease up for 1-2 laps. I run in White Solo (as classified with PCA) and have started competing in an endurance racing series earlier this year, so I more or less know what I'm doing on track. Also going to VIR in November is by design (cooler ambient temps).

The transmission also appeared to overheat when I was driving in the mtns. The 3-4 shift in particular got very sluggish. Are there practical solutions to cool that as well? I suppose it wouldn't be fair to not mention that this car is also slightly modified. Full exhaust, ROW intake and an ECU tune so I'm guessing its putting down 575ish hp. So I realize that can put additional stress on the transmission.

This car is a HUGE departure for me (I cherish lightweight and manual transmissions) but I'm trying something different! Now, if I fall in love with this car on track, then I will look into that oil cooling solution.

Diabolis

Yeah... I know. When I first got mine it was meant to do double-duty as a sporty "daily driver" & occasional weekend track toy. It could do it in late October and was neck-in-neck with well-driven E9X M3s - but most certainly not in July or August when it would go into limp mode after four laps.

What you likely experienced with regard to the sluggish shifts is the engine puling back timing, which does affect the transmission shift times, in particular on the MCT cars that readily exhibit the problem. The TCU performs the shifts based on input from the ECU, and it is very likely trying to minimize MCT clutch slip during the shift itself in an effort to keep the oil temperatures under control. While for more serious track applications a trans cooler may be needed, it is nowhere near as essential as an oil cooler for the occasional lapping day. The only person I know that is still active on the board and uses the C63 as a regular / only track toy is @BLKROKT, but I don't recall whether he has a dedicated transmission cooler. The LSD could also use some additional cooling.

With the 44O kit on mine, a larger capacity finned transmission pan (Weistec), LSD casing with the "rectifier" cooling fins and upgraded brakes, I was able to track the car without any mechanical issues in the heat of summer, unless you count the eventual and repeated creaking of the sunroof cassette after every event from the chassis flexing. It is a nice track car - albeit quite heavy - and I still take it out on track for one or two sessions a couple of times a year, but it is to clear out the proverbial cobwebs. As a regular track toy, after going through three Porsches myself, I decided to get a C5 Z06 that was specifically built for track duty and have never looked back. I am actually considering selling the C5Z and upgrading to a full-blown C5Z race car or a C6Z race car that has been essentially been transformed to C6.R spec (down to the racing transmission) if we can make the numbers work on the second one... much lighter, much faster and INFINITELY more cost-effective.

Am just about to get suited up again to do my second stint at the LDRC race at Mosport. The weather is miserable and people are going off all over the place... plus the fog is getting worse. I might be at VIR for the December 4-5 ChampCar enduro, G-d and COVID willing... perhaps we'll meet there!

BLKROKT

Yeah I have dedicated diff cooling already, but the aux trans cooler pump etc has just been sitting in a box. I’ll get back on that over the winter, but the car absolutely needs it.

You should be fine at VIR in Nov. Before my 44O kit and with the radiator block off plate, I could lap in manual no problem up to about 85F ambient. Oil temps were high, but no limp.