Castrol Syntec 5w50 overkill for my application?

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Dan, if you want a thick oil the M1 10w-40 HM is a screaming good choice. imo, the 10w30 is fine for winter. You have a big sump, the chance of overheating the oil is MINIMAL.

Remember when you look at the recommended grades, the 5w30 that Audi oks is actually the thicker Euro 5w30s. Thin USA 30 is not a good choice for your engine outside of arctic conditions. There is also no provision for a 10w30 in Europe. All the spec oils are 5w30, so I suppose there just is not any 10w30s on the market there.

Anyway, the M1 HM 10w30 is so thick, it makes the thicker ACEA A3 spec, with HT/HS over 3.6cP or even 3.8???

I'd get one jug of 10w30 and 10w-40 (10q), add all the 10w30 and most of the 10w-40, saving 2q for top-off.

Stressing over an oil for your app is unnecessary, the M1 HM is very cheap and very good. Easy to find too.
 
Yes, the SLX Professional OE 5w30 is extremely heavy for a 5w30 (KV @ 100C is 12.0), basically the same as GC.

And yeah, the 10qt sump really helps. I'm waiting for JHM to reply back with their oil temp data. They designed a new oil cooler for the car and have lots of experience with this.

The M1 HM 10w40 isn't terribly thick, actually -- it's about the same as M1 TDT. Red Line 5w40 and 0w40 and RLI 5w40 are much thicker (nearing Xw50).
 
Yes, hence my interest in not using $14/qt Motul 300V if possible. Good oil (car feels great on it) but $140+ in oil + $20 filter is a LOT to spend every 6-8 months.

You ought to see the Niagara Falls during an oil change...
 
Just stumbled across another 5w50 that has a KV @ 100C of 16.3 -- that's right at the minimum limit for 5w50s, meaning that it is (for all intensive purposes) a very thick 5w40. It actually has a 40* KV lower than Red Line's 5w40 with a strong VI of 178 (large ester content). HTHS is "above 3.7"...waiting to hear back from the mfg. TBN & NOACK are unknown.

A tad pricey at $13/qt compared to M1 5w50's $8-9/qt, but it sounds like it has significantly better basestocks.
 
What bothers me about the RP XPR is that there are no published figures for it (KV, VI, HTHS, etc). Kinda hard to make a decision based on marketing statements alone.
 
Why do you want it so thick for winter in a stock non-turbo engine with a huge sump?


fwiw, the 5w-50 M1 numbers I crunched, it looked like a 10w30 dino in cold, getting thinner below -20c.

From +30c to >+100c, the 5w-50 is very similar to 15w40, almost identical.
 
Originally Posted By: dparm
Just stumbled across another 5w50 that has a KV @ 100C of 16.3 -- that's right at the minimum limit for 5w50s, meaning that it is (for all intensive purposes) a very thick 5w40. It actually has a 40* KV lower than Red Line's 5w40 with a strong VI of 178 (large ester content). HTHS is "above 3.7"...waiting to hear back from the mfg. TBN & NOACK are unknown.

A tad pricey at $13/qt compared to M1 5w50's $8-9/qt, but it sounds like it has significantly better basestocks.


What 5W-50 is it!? And yeah, that IS a Thin 50! But which kind. You did not tell us
smile.gif


That engine is well protected. This thread DOES being up the question, and ill Bold it:

HOW important is the W number in apps in Summer! Is it "Completely irrelevant," or is the Lower W number ALWAYS desirable! What is "Shearing"'s involvement?
 
So far I am unsure if I need to make the move. Respected aftermarket company JHM is going to provide me with their oil research that led to the oil cooler kit/radiator delete. I am also debating moving to Red line 0w40, German Castrol, and a few others.

The S4 has a large high performance motor in a very tight space. It has 3 radiators just to deal with the heat and even a water-cooled alternator. Opening the hood after driving around town and it's like a [censored] furnace. And with my driving habits and track time, I want this motor to get the best protection it can.

Care to expand on your "number crunching"? Not doubting, just curious what you did.



HangerHarley...it's Maxima Maxum4 Ultra. Technically a motorcycle oil but totally fine for cars.
 
If you are doing track days in this car, I think you should use the thickest 502/505 oil you can and call it a day. It would give me pause to abandon the VW specs on the oil.
 
I forgot or missed the track time reference. DO you do that in winter? Come summer, I would def consider SynPower 20w-50. I have some Valvoline 20w-50 Racing I got on BOG0 after rebate. I'll mix it with the 10w30 R for my app.

fwiw, my BOSCH mechanic uses Syntec 5w-50 by the drum and swears it's better than other 50 weights...however, he uses VR-1 dino 20w-50 in his UrS6 with 18lbs of boost. He changes it a lot. Original KKK turbo still.
 
I do some occasional ice racing in the winter (maybe once a month). I don't think I'm adventurous enough to run 15w50 or 20w50, though I know there are some track junkies with S4s and RS4s that do it. I suppose I could run it from about April to October? (temps are consistently 40+)

Motul actually has a 5w50 that's fairly light too, and that Maxima oil is tempting as well.
 
SynPower 20w-50 supposedly has some PAO content.

If you are ice racing, I'd say to change the driveline fluids to freshen them a bit.

Mobil 1 75w-90 is fine for the diffs, but maybe go a hair lighter for the trans, like Redline MTL 75w-85. That 12cSt mix has been standard for Audi owners in cold temps for a long time.

All things considered, I don't see that a 5w-40, even Rotella, would fail you. Mobil 1 TDT is somewhat thick.
 
I already run Motul Gear 300 in the trans and rear diff.

Ideally I'd like to run the same oil year round (hence the 5w50) since my driving habits are rather unusual and my mileage is low, but I suppose I could run a 0w30 or 0w40 in the winter and switch to a 15w50 or 20w50 for the warmer months. I'll read up on the specs for some summer oils.
 
Originally Posted By: dparm
I already run Motul Gear 300 in the trans and rear diff.

Ideally I'd like to run the same oil year round (hence the 5w50) since my driving habits are rather unusual and my mileage is low, but I suppose I could run a 0w30 or 0w40 in the winter and switch to a 15w50 or 20w50 for the warmer months. I'll read up on the specs for some summer oils.


You analyze things the same way I do!
smile.gif
And i came to the conclusion... 5W-50 DOES seem attractive. I may get a Redline in my old beater. Its realy thick and actually seems to be thicker AT temp than their 15W-50.. ?? (If there is no Fuel dilution, it may be a winner.) Why do you think something is too thick and you are looking at "Thin" 50s?

Id honestly give a Redline, of most any grade (5W-50, 15W-50, 10W-40 since it says it has a stronger film than a non-synthetic 20W-50) a shot and see how that Teuton likes it. It likely will. If that checks out, you have found your oil.

As for changing with the season, i figure.. if it is one of those 40 degree days and you decide to take a two hour trip AFTER using the car all day, your choice of a nice thicker 40-or 50- maybe even this RedLine will serve you well. Even WITH all that heat. Think of how it is in the engine bay.. Sounds like your Oil temps are around 220, maybe hotter. See how it likes the redline, then try the castrol. My car seemed pretty decent on it, and if there are no other issues (?) then there you go. Especially for "Light track" use.. It all adds up. I vote one of those two previously mentioned. (Same holds true when the heatwave comes and its 105 degrees, OR you go to Miami and its 112 degrees. Then drive back to "Chicago" and its 50 at night. No biggie. Drive through Death Valley. Its all good. On those oils...)

Castrol 5W-50 IS likely a great year-round oil too, since if its cold pumpability is more like a 10, its still within the range for your "Not really colder than 40" temps. Yet another nod for the Hydrocracked Group III 5W-50 that is on sale at Autozone every two months.
 
Pending the results of my Motul 300V UOA (halfway point to my next change), I am probably going to go for the Maxima 5w50. It's the light 5w50 with ester basestocks and a hint of PAO(no group 3 at all). I talked with the company president and he actually said it's totally fine for auto use though the ZDDP levels are higher and it could eventually foul a cat. He also gave me the specs: TBN is over 10.0 and the HTHS is 4.58.

He runs it in his wife's Lexus and has for a long time.
 
Eh, not much cheaper than Motul but easier to get since several local shops keep it in stock (no shipping charges).

If I can snag it at a good price locally, I'll do it. Otherwise I think I'll stick with Red Line 0w40 which is fairly heavy and robust.
 
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