Castrol Syntec 5w50 overkill for my application?

Pennzoil motor oil
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Originally Posted By: dparm
Interestingly, both Mobil 1 5w50 and Castrol Syntec 5w50 have the same KV @ 100C of 17.4. That makes them very light 50-weights. (as opposed to Syntec 20w50 that is 19.7 and more in the middle)

The oil in the sump right now has a KV @ 100C of 13.32, making it a light 40.

Mobil 1 5w50 does carry VW 505.00, which surprises me. That would actually mean it's okay to run in my car (needs 502/505).


Castrol 5W-50 you can find. Mobil 1 5W-50 is like NOWHERE!

You can even get PP 5W-50 did you know that. I wonder what 15W-50 would be bettewr/worse for than!
 
I can order Mobil 1 5w50 online, not worried about availability. Just worried more about the 50-weight being too much for the motor. There are some guys who run 15w50 in the same motor because they track the car a lot. I track/autox occasionally, but I drive hard on a daily basis.
 
Originally Posted By: Audi Junkie
Not too thick and it will shear anyway.


It wont shear too much its a thin 50 to start with so its not "Too thick." Gives good protection, most likely dont need the Mobil. Their Siytec 20W-50 is next to inpossible to find, Anywhere.

I say go for it. It is great for Euro cars, if not a 5W-40. But i say its good.
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btw, with a 10-qt. sump, buy the 2 specials a day at AutoZone for $27.99 PLUS FILTER IS INCLUDED!
 
My car uses one of those huge cartridge filters, those aren't valid for the deals. Plus Mobil 1 5w50 isn't available in retail from what I've seen.
 
Originally Posted By: dparm
My car uses one of those huge cartridge filters, those aren't valid for the deals. Plus Mobil 1 5w50 isn't available in retail from what I've seen.


Right. When i got my deal on a large sump I had, i just got "Any qualifying filter" Since ANY Syntec is AFFORDABLE on the deal. Get the right filter. 10 is even larger than the one I had!

But yeah, as long as Syntec does not leak out (?) I think its a good oil. Whatever they did with it, it most likely WONT "Shear" past a 40-weight, and its a thin-50 so if it were to, you have good flow. Thick, syrupy 20W-50 some cars may need it, sure, but the '50' high number makes engines feel great. The 5W, 15W, or 20W number preceeding it? The 5W-50 at least. I mean, it indicates good flow, OR a nice thin-ness (for its grade) through its spectrum.

I personally think it replaced their 20W-50. I do.

i can also linky PP 5W-50 AND 15W-50. Go fig that one!
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Red Line's 5w50 is way too heavy, for comparison: KV @ 100C is 20.5. Although it has a great VI and high HTHS with low NOACK, it's not a good choice.

Mobil 1 5w50 is almost like a 5w40. For comparison:

Mobil 1 Turbo Diesel Truck 5w40: KV @ 100 = 14.9
RLI BioSyn 5w40: KV @ 100 = 15.8
Mobil 1 5w50: KV @ 100 = 17.4
 
The cold flow of a 5w-50 isn't as good as a 5w-40. It's more like a 10w-40, which brings me back to Mobil 1 High Mileage...
 
Originally Posted By: dparm
Red Line's 5w50 is way too heavy, for comparison: KV @ 100C is 20.5. Although it has a great VI and high HTHS with low NOACK, it's not a good choice.

Mobil 1 5w50 is almost like a 5w40. For comparison:

Mobil 1 Turbo Diesel Truck 5w40: KV @ 100 = 14.9
Red LineI BioSyn 5w40: KV @ 100 = 15.8
Mobil 1 5w50: KV @ 100 = 17.4


What is the KV @ 100C of RedLine's 15W-50?

And Why are we insisting on 5W-anything? I can order PP 5W-50 and 15W-50. Unless we dont want PP in your car?

Idk, 5W-50, this Syntec should do its job, Mobil 1 High Mileage 10w40 seems like youd NEED to stay in the Mobil family. After all, some do. Here the facts are looking good for Castrol's Thin 50, its not a Heavyweight like a Red Line 5W-50 (?) and an Mobil 1 is being suggested.
 
On recommendation, my buddy used Rotella T5 10w30 in his S4 4.2 with great mpg, "the best ever" he said and consumption was halved over the synthetic oils he tried.

I don't see the point in VW spedced oils in this engine.
 
Hmmmm.

dparm, what grade does the engine "Spec?" I cnat help but think a thin 50 is great for you. Like the 5W-50.

I checked out Redline, and their 5W-50 IS Thicker (100degreeC KV) than their 5W-50! ?

HT/HS is also pretty good on the Castrol. It is just below a 4, or right at a 4. Need to see a PDS again, but this is a close race!

If its on sale, there ya go... Syntec 5W-50 with the sale, filter separate and not at auto-zone (just get one of anything for the special.) That was an issue too, right?
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Most the others have to be mail-ordered.

Also, what does the RS4 use? Ill google it... Seems to want 5W-40, even in an RS4 "B7" ? So maybe 5W-50 is fine.
 
RS4 is a different motor, not a fair comparison. 32V, direct injection, higher redline, etc.

My car is spec'd for a VW 502/505 oil that's 5w40, 0w40, or 5w30. 0w30 would probably be safe too but none are listed on the approved sheet.
 
Originally Posted By: dparm
RS4 is a different motor, not a fair comparison. 32V, direct injection, higher redline, etc.

My car is spec'd for a VW 502/505 oil that's 5w40, 0w40, or 5w30. 0w30 would probably be safe too but none are listed on the approved sheet.


Cool! Simple then:

1) Castrol Syntec IS Specifically made for your car.. 5W-40. (It says so, by Castrol.) 2) Castrol Syntec 5W-50 IS a thin 50, and likely an extension of the engineering done on the 5W-40, hence the "5" W-rating kept.
3) If you are going to get the Oil temps up, im sure the 5W-50 would be up to task.

I learned something new about Redline's 5W-50 being thicker at operating temp than their 15W-50. Whoa! it also says their "10W-40 will provide more film strength and lubrication than a Conventional 20w50." Pretty telling statement! And one I like.

idk, Dparm. Its your call bud.
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Correct, the dealers stock Syntec 5w40 and SLX Pro OE 5w30.

If I do make the move to Mobil 1 5w50, what are some things to look for? How will I know if the motor isn't liking it?
 
Red Line's 0w40 is actually looking attractive too. It's a very heavy 0w40 (KV of 15.1) versus Mobil 1 0w40 (13.5). Very high VI and very low pour point as well. Higher HTHS but slightly lower TBN (not worried since I drain every 5k).

How would I know if the oil is too thick? What are signs of an overly heavy oil?
 
I would go with Redline 5w-40 or Mobil 1 0w-40.

Also, I would look at the cSt values at 40C and compare to Syntec 5w-40 or factory fill.

Do you have an oil temp gauge? If so, does the temp get high enough to worry about HTHS values?

Do you drive the car hard in the winter?

What are your OCI?

All things to consider, IMO.
 
The KV 40C value of factory Castrol GTX Magnatec (Syntec) is 74.0. For Mobil 1 5w50 it's 104.6, and for Red Line 0w40 it's 81.0.


No oil temp gauge. I drive the car hard 12 months a year, but I always baby it until it has warmed up. OCI is typically 5k which works out to about every 6-8 months for me (car is not a DD).


Perhaps I'll try the Mobil 1 5w50 for the next change and get a used oil analysis at about 2500 miles to see how it's doing.
 
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Upon reading more (thank you, search function), I've got a better understanding of how a thicker oil than necessary will indeed cause problems. It will not pump in sufficient volume to the top of the motor which causes excessive wear; an oil that's too thin will end up shearing and need to be changed faster, though it really won't damage things.

I'm sure Audi chose 0w40/5w40/5w30 as the recommended fill because it would satisfy the driving habits of 99% of drivers. However, there's that 1% of us that drive abnormally (weekend racing, excessive time at WOT, etc). I'm simply trying to determine if I need to move to a different oil because of that.


What has me most concerned is that 5w50 has a 31% higher KV value than my current 5w40 fill (at 40C) and 24% higher at 100C. Curiously, my existing 5w40 actually has a slightly better HTHS value than the Mobil 1 5w50 (about 5%). VI is basically the same.

Waiting to hear back from an Audi aftermarket company with extensive experience in this motor -- hoping they have oil temp information.
 
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