[s-cars] Castrol GTX High Mileage Oil - the real issue is not "seals"

[Scott Justusson]

Sigh, here we go again....  This has nothing to do with seals, swelling or (OMG) the switch from synthetic to dino oil.  This is an educated mechanic legitimate concern about M1 products reducing the levels of Zinc and Phosporus to comply with the lower EGR/catalyst effects of wear additives, driven by the EPA>Car Manufacturers.  One might argue that, esp on cold start, an engine at 245k would benefit from extra ZDDP(dino)/ZDTP(synth) Zinc and Phosphorus.  Previous levels were in the 1100-1300 range, the new standard is sub 800.  M1 Claims this change is safe for new and 'old' vehicles, but I think that is plain marketing BS.

The best compromise to the OP IMO, is to switch to M1 Turbo Diesel Truck Oil or a Delvac Synthetic, as both retain much higher levels of cold start/worn engine tolerance, wear barriers.  Short of that, a change to a Castrol dino product will yield the same results.  

As a rule I don't enjoy engine oil discussions, but dragged in by a point-by, happy to back up the educated mechanic recommendation and concern, than anyone focused on 'swelling seals' totally missing the legitimate issue.

BTW those in select states might just find that M1 Turbo Diesel Truck oil by the gallon at Autozone, is less than Wallyworld brand dino oil.  BtstockeduponT

Taka, you just try to hard, it's the Holidays, and it would appear Mr Rodrigez educated mechanic is just looking out for a good customer.

Cheers

S "Taka point-by again" J
95.5 S6 M1 Turbo Diesel Truck OIl


 

-----Original Message-----
From: Taka Mizutani <t44tqtro at gmail.com>
To: s-car-list <s-car-list at audifans.com>
Sent: Mon, Dec 16, 2013 2:50 pm
Subject: Re: [s-cars] Castrol GTX High Mileage Oil


I would not do that myself- going from full synthetic to a conventional oil
with seal swellers doesn't really make sense to me, especially if
you've had no issues with running synthetic. The synthetic will last longer
and be more resistant to viscosity breakdown, often has a lower
pour point and a higher flash point.

However, you should ask Scott because I am not qualified to answer any
questions about cars at all.


On Mon, Dec 16, 2013 at 2:56 PM, Thomas Rodriguez <trodri69 at gmail.com>wrote:

> My '95 S6 has 245K miles.  Head was rebuilt about 40K miles ago but
> otherwise the engine is original. I've been using Mobil 1 5W/30 synthetic
> motor oil for as long as I can remember. Engine runs strong. I add about a
> quart between scheduled oil and filter changes every 3K miles.  Otherwise
> there are no signs of burning or leaking oil.
>
> Last week my mechanic recommended we switch to Castrol GTX High Mileage
> 5W/30. I agreed and have driven about 300 miles with this oil in the
> engine.  I understand that this oil is not synthetic.
>
> Any thoughts about using the Castrol GTX HM oil?
>
> Tom
> '95 S6
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