Looking for UOA with oil treatments

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Aug 10, 2014
Got a 2002 Land Rover Discovery II with 133k miles, low oil pressure. Too long a story to type here but suffice it to say that I have checked it mechanically and the cost to repair the mechanical bits to correct the oil pressure is more than the truck is worth - however it is my daughters transportation and I would like to avoid buying another one as long as possible.

Currently have Valvoline High Mileage 20w50 in it, previously tried Diesel 15w40 with no change in oil pressure (7 at idle, around 30 at 2500 rpm, mechanical gauge). We live in South Carolina so low temperature days are few and far between - however I am reluctant to dump simple viscosity thickener in due to additive dilution.

Seems the discontinued Valvoline Syntec Oil Treatment was well thought of from a additive and viscosity modifier standpoint but no longer available.

Looking for some UOA's that show effects of currently available treatments - mostly looking for high viscosity at 210 F without significantly higher viscosity at 40 f (or room temp). However I can't seem to find any UOA's with treatments included - anyone have any idea why?
Most vehicles I've owned will give you 10 lbs or less at idle, and approx a 10 psi jump, for every 1k rpms the motor is spinning. Up to a certain rpm. Usually between 3-4k .I wouldn't worry about having 30 psi at 2500 rpms. What does the manual say yours is supposed to be?.,,
This isnt meant to be mean, but the mext time she wants a disco for a vehicle...tell her no.

Low oil pressure today, a million issues tomorrow. And they are one of my favorite 4x4s.

Dump a quart of 20w60 motorcycle oil in there.if you are worried.
Oil pump relief might be open. Inspected for sludge or crud yet?

What oil filter?

I've never seen an issue with any of the oil molasses. Feel free to use a pint of any...stp blue/red, motorhoney, hyperlube, or either Lucas treatment.
Thick oils are a band aid. The light goes off but lubrication suffers.

I would be using a 10w40 high mileage. Your oil pressure doesn't seem disastrously low yet and overly thick oils cause more startup wear.
Originally Posted By: Extinct
Looking for some UOA's that show effects of currently available treatments...

You can look at the last UOA on my Accord. I specifically did not want to increase viscosity, so I combined it with a thin oil, but it still might be interesting to you.
133k miles imo is VERY low mileage for a high end car like that. Out of curiosity,what exactly did they tell you was wrong with it? Did Rovers of that vintage spec a 20W50 (I've read Rovers spec that weight,just don't remember what years)? Is it having a compression problem? If so,how about 20W50 plus a can of Restore? Some people swear by that stuff for old/worn engines.
Your oil pressures do not seem that low... I would try an OCI of Rotella T6 5W40 syn and see how the oil pressure is. I would bet it will be the same as the 20W50 and it has a good chance to help clean up any issues that you think your Land Rover may have.
From what other BITOG members have said, it appears that L-M MoS2 helps worn engines more than any other additive. L-M also makes this claim. It doesn't thicken the oil up, it helps to "heal" or mitigate some of the damage.
Sorry I did not rspond sooner. I will try to answer some of the questions:

1. Manual says it should idle at more than 10, and pull 25 psi at 2500 rpm. Ours is right at borderline with those numbers using 20w50.

2. Well aware of the Disco issues, good for first drivers - 5k lbs, full frame, good visibility, won't go over about 70mph.

3. Wish I had know about 60w oil before I spent the money on the 50w

4. Pulled the oil pump relief valve, and one of the rod bearings. Relief valve is not stuck, rod bearing is not worn excessively. Oil pump gears also were not worn. Did not pull the main bearings but that is unlikely given the rod bearings. Oil filter is oversize Mobil 1. Likely a PO extended oil changes too long, wore out the cam bearings.

5. Thick oils on worn engines allow for oil pressure ie a film thickness between bearing and crank. No oil film/pressure = spun bearing and game over. Start up wear is largely a myth. Positive displacement gear oil pumps remain primed and within a couple of revolutions have pressurized the crank and rod journals - and there is adequate film strength and residual oil from the last shutdown to prevent startup wear on the bearings (pistons, rings, cylinders are different story).

6. OEM spec is 10w30, but this particular engine needs 15w40 diesel oil because it needs the zinc for the flat tappets. 133k miles is relatively low for this engines problems, I have an identical one 2 years older and it idles at 25psi and runs 45 psi at 2500 rpm. Bad one likely had a PO who did not change the oil as recommended.

I was looking for a strong viscosity modifier additive, as this particular engine has ok oil pressure when cold but drops perilously low when warm. 20w50 high mileage did not correct the issue. Did some research and the STP oil treatment seems the only one that that seems to have a significant viscosity modifier package (does not temperature thin as much). Used 2 cans of the STP with minimal change in hot OP - we will have to see how long it holds out.
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