Thought I had already posted it, but guess not. It's kind of dated but may be useful to some. Doesn't look like the GTX will do a 5,000 mile OCI under these conditions.

2000 Ford F150 w/5.4L, auto trans, tow package. Driven 6 mi one-way to work (apx 15 min run time) in ambient temp of 40 deg winter a.m.'s, 60 deg winter p.m's, 70 deg summer a.m.'s, 80-90 deg summer p.m.'s. First oil change at 2,000 mi. All subsequent changes at apx 5,000 with GTX at American Fast Lube. (Changed "early" this time as I am now towing a 3000# boat on the weekends as much as I can.)

Miles on unit 31,137. Miles on oil 3,782. Time on oil 5 months. No make-up oil. Castrol GTX 10w30 from bulk. Warner (Champion Labs) oil filter. Air filter (Warner - ? on mfgr) replaced at apx 15,000 miles and this change.

Test done by Blackstone on 7-11-03.

ALUMINUM 5
CHROMIUM 1
IRON 19
COPPER 9
LEAD 0
TIN 0
MOLYBDENUM 43
NICKEL 1
MANGANESE 1
SILVER 0
TITANIUM 0
POTASSIUM 0
BORON 4
SILICON 9
SODIUM 2
CALCIUM 1695
MAGNESIUM 6
PHOSPHORUS 775
ZINC 966
BARIUM 0
SUS @ 210F 56.6 (mid-20 wgt)
FLASH 410
TBN 1.2
Fuel, AF, H2O & Insols within range.

Blackstone comments: "Nothing too unusual ... all wear read well within the average range for this type engine, which is a very good indication of normal wearing parts ... normal wear after about 4,000 miles on oil ... good oil filtration ... TBN was low ... [TBN] probably started out around 7 ... viscosity was low ... try 4,500 on the oil next time."

My Comments: TBN indicates oil is shot. Leave in for 4,500 miles? No way. 3,000 max with towing this summer. Oil sheared down big time. It started off as a mid-30 weight. Doing an Auto Rx cleaning now before switching to either Chevron Supreme 10w30 or Pennzoil 10w30. After seeing Brian A's Chevron UOA ...

 

Thanks for sharing your results. Even with mild temperatures it looks like short-trip driving has really taken a toll on that motor oil. 15 minutes is not long enough to get the oil temperature up to normal and evaporate moisture. Your TBN number tells that story pretty well. A 3000 mile severe service schedule is in order.

I'm surprised that the viscosity is that low. 10W-30 does not need the amount of polymers that 5W-30 needs and Castrol makes a big deal about shear stability in GTX adverts.

Jim

 

Doyall,

Agreed. You got a pretty good handle on it. 3K when towing may end up being a bigger factor than any of the top tier oils you're chosing between.

0 lead...sweat!