Long Drain Intervals

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Jan 16, 2003
Shippensburg, PA
I saw this in another post and now I am scared:


Anyway, the impression I got from your e-mail is that while this oil is very tricked out and VERY effective, one should be carefull with long drains of 10k miles of more due to its composition.....therefore, the need for LC20 as you've suggested in the past to evade oxidation for as long as possible.

I am coming up on 7000 miles and 8 months in my 95 Mustang, with some hard usage thrown into the interval. Should I be dumping my GC NOW?!?! I realize that 7000 miles is not 10k miles, BUT, this oil was in over 8 months, and it saw cold winter start-ups and some drag racing.

Dump it, or run it to 8k and get a UOA as planned??

IMO, go to 8k and get the UOA. While my little Hyundai is nowhere near the same as your Mustang, at 7400 miles, I could have easily gone to 10,000+, and this was with just GC, no LC or FP.
novadude, the answer is in your post.

Get the UOA now, and then decide whether to dump it or go to 8, 9 or 10k miles (and hopefully, for SCIENCE!, do another UOA) And get the Dyson Analysis, it is so worth it IMHO.

What do you really think Terry is going to say differently? Even if you know exactly what conditions your car operated under, there is no accounting for unforeseen (by definition, no?) problems that can be detected by a UOA. So get the UOA and share your results with us

My prediction? With some drag racing, and a wicked cold winter, you're probably going to see some elevated lower end bearing wear (Pb). If you don't drive often enough to fully warm up, you may see some water and/or fuel dilution, which could directly or indirectly cause viscosity drop. If you see these things, don't freak out, they're to be expected... just use that info to guide your OCI lengths in the future. Paulo the Prognosticator has spoken!

[ May 04, 2005, 02:07 PM: Message edited by: bigpaulo ]
I already use Terry's services.

If I send a UOA, I am dumping the oil... I don't have any desire to track down or use a pump to siphon oil out of the dipstick tube. The only time I will do a UOA is if I am draining, and I use the information to establish the next interval.

Terry has seen this engine with Pennzoil 10W-30, but this is my only my second GC interval, and I did not have the first one analyzed.
I think you'll be fine to go to 8k. My last UOA in my 98 Corvette with GC was a 6k run through the winter, with lots of drag runs from the beginning of the interval (just before the strip closed for the season)

This is what that report looked like:

6100 miles on oil
Oct 11-Feb 19 (4 months)
43,000 miles on the car
German Castrol Syntec 0w30
K&N HP1007 oil filter
K&N air filter
LS1 5.7L V8 engine
Daily driver with a lot of rush hour traffic
14 quarter mile runs
7L oil capacity
No oil added (none was needed!)
Oil life monitor indicated 18% oil life left
Analysis by Wearcheck Canada

Iron 9
Lead 2
Aluminum 3
Copper 2
Chromium 0
Tin 0
Silver 0
Titanium 0
Nickel 0
Silicon 7
Potassium 2
Sodium 0
Boron 5
Barium 0
Calcium 2790
Magnesium 129
Moly 9
Phosphorus 782
Zinc 930
Fuel 0
Glycol 0
Water 0
Oxidation 63
Nitration 55
Viscosity 12.4 cst at 100c
TBN 4.22

I have recently started using Terry's services myself... good stuff.

Sorry, I was assuming you could take a sample without draining the whole shebang... man, here's another plug for the Fumoto oil drain valve, that thing is super! Get one. It's worth it just to keep oil drains on the neat side, and super-worth it to take mid-OCI oil samples.


That's some awesome wear numbers for having "dragged" that car! You said lots of rush hour traffic, but did your car get to full operating temperature everyday? That goes a long way to evaporating any water and fuel dilution. And a 7 liter oil capacity doesn't hurt, either!
My car always gets up to full operating temperature on every trip, since my trip to work usually takes 45min, and going home usually takes 60 or more. So even in the winter, my oil temp would be over 185F for more than 50% of the trip. I definitely agree that helps a lot in the oil life. It also helps that my oil doesn't get too hot either, since it doesn't often go above 207F. Most of the time it's sitting pretty close to 200F actually.

Another reason for the low wear is that most of the time I won't go full throttle unless the oil is above 180F. (sometimes at the drag strip I have no choice but to go full throttle when it's been sitting for a little while and is a bit colder, but never was it below 150F)

Originally posted by blupupher:
Patman, did you add anything to the GC? Just curious because the Moly is 9? Isn't GC 0 new? Mine was after 7400 miles.

I did not add anything, but since it was only my second run with GC, there is still some residual moly from the previous oil (which was most likely Mobil 1) Some of the moly (1 or 2ppm) could be from the rings too. GC's VOA does indeed show 0 moly.
Nova, why don't you email me this kind of question, you are a customer and I care.

Measuring the oil with analysis will give you the emperical data you need. But if waiting is better for you then......AND the engine does NOT any have any known issues let it rock to 8K.

Relax and chill man...

I went 6mo / 11k twice on GC. I wish I UOAed it, oh well. I will now be doing 4mo / 7.5k due to my ever-increasing supply of GC and now I DIY oil service rather than dealer service. (found my "new" dealer-installed Mann filter to have corrosion on the base after 1 month duty.
) The dealer guys treat me very well, hard to imagine them billing me for a filter and re-using the old one, but it was quite corroded. Maybe my imagination, but DIY now.
Audi Junkie,

A corroded filter? I've only seen that on an occasional beater that probably had the filter on the engine for literally yrs and was no doubt operating in bypass mode.

Originally posted by cos:
Audi Junkie,

A corroded filter? I've only seen that on an occasional beater that probably had the filter on the engine for literally yrs and was no doubt operating in bypass mode.

Does corrroded include rust on the baseplate of a filter fresh out of the box, because if it does, I have seen that.........more than once.
Wow, rust on a filter? I've got AC Delco filters in my house that we bought 1993 during a going out of business sale at an autoparts store near us. My dad stockpiled them like people stockpile oil. We still have some and none have rust inside, one of them is being used on my moms car right now.
White scale like from salt, but it definately bit into the white metal. No biggie at this point, I dumped the filter and GC at 1 month for ARX.
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