I checked my oil pressure the today,I have a gauge but the feed wire was too short so while I wait I setup up a temp solution.

Oil in use Mobil Vr1 10/30 Synthetic - it has better performance than the Rotella 15/40
Filter M301
I do have a tick hence the pressure testing

Seems good cold idle at 50 PSI idle at 188.6 ,normal hot idle, around 18 psi 680 RPM, Hot 2000 around 42 ish

For reference the RAVE 50 at cold idle and 10 minimum, it should run between 40 and 50 at 2000 + rpm hot

I have a few concerns related to hotter summer temps, so I may move up to AMSOIL 20/50 synthetic for the summer

Some Images

The test setup Glowshift Gauge and Sender, Switched lead to horn. Everything else to battery, connected by pressing wires to terminals via alligator clips. (Very High tech)
My monitoring cell phone leaned up against gauge




And the results over time for those interested, I have no issues with these numbers but I suspect they will be lower in very hot temps.

 

Perfect! Good job. You may want to stick with the diesel oil at the higher weight in the summer, in addition to the higher zinc content it has additives to deal with the higher soot loading in the diesel engine. Soot is very similar to the carbon sludge most Disco's have internally due to the factory pcv setup, the additive helps disperse the carbon build up so it is caught in the fitler: https://www.machinerylubrication.com...oot-oil-engine

 

@Extinct Yup reading about the various oils,zinc content. etc hurts my head some days there is some much contradictory info. I have Hot rod forums are actually a pretty good place to sort some it out lots of old push rod engines in use in that group. Very different setups as far as usage but good general info.

 

I was going to set into a diatribe about high zinc being important in these engines and touting Valvoline VR-1 20w50, but after looking online to confirm a few facts I discovered that Amsoil does offer high zinc, at least in its synthetics anyway, perhaps others as well. I'm a big fan of 20w50 in my old BMWs and even ran Amsoil for years before switching to VR-1 about 15 years ago, however I'm not sure that's right for a Disco. Emphasis on "not sure". Usually those thicker oils are better used in engines with lower manufacturing tolerances where there's a lot of gap between moving parts, unlike today's engines where 0w20 is pretty common due to much more accurate machining. As descendants of the Buick 215 V8, 20w50 may not be a horrible choice, don't forget, we have old pushrod engines too! My biggest concern with the 50 side of the equation is how high these engines rev on start up. 20 seems to be a good weight where sustained high temps are prevalent but 20w50 is pretty thick at ambient. I cringe every time I start my truck and it shoots up to 2k as things start flowing, and I'm running Rotella T4 15w40 Diesel .

Keep in mind that an oil temp gauge is a much better indicator of operating temps. It takes a good 10-15 minutes of the coolant being up to temp before the oil hits its stride. The best time to feel confident about your oil pressure is when you get off the highway and sit at a traffic light for 60 seconds when it's 95° out. If you've got 15psi or more then, you're in great shape.

Edit: My 535 has 492k miles so I've done quite a few oil changes on it and feel pretty confident I know what I'm talking about.

 

@ahab Thanks for the feedback. I believe Amsoil has a 10/40 that would be a nice year round oil in this is part of the world there are a few other options but it is painful to figure out the zinc levels. I ran the 15/40 rotella myself but there was a lot of sludge and varnish build up, likely from extended oil use by the PO. I thought I would try the VR 1 as it suppose to have better overall protection.

20/50 is what RPI recommends as well as a few other LR centric sites, but I like to see what is going on in my truck. Also why I tested the oil pressure today.

 

The zinc levels are a bit of a knife edge given what it can do to catalytic converters however that hasn't been a concern for me in the last 10 years since all my other cars are old enough, or mileage exempt, such that emissions testing has ceased. Not the case with the Disco for another few years however. From what I'm reading, Amsoil's ZRod 20w50 comes in at 1400 and the VR1 is 100 PPM lower. The Rotella T4 claims another 100 PPM drop at 1,200 PPM. Here's a pretty good link on a somewhat reputable site with some info directly from Valvoline regarding what PPM is appropriate for engines like ours.

https://www.bobistheoilguy.com/forum...zddp-is-enough

It's also interesting to note that Valvoline does not recommend using VR1 in vehicles with cats so if emissions is important to you that's a crucial consideration. Rotella however doesn't seem to offer any stated guidelines but notice that they specifically call this "diesel engine" oil, where cats aren't an issue.

Heading into the summer, now's the time to try out some 20w50 weight oil and compare what your pressures look like. You definitely won't want it in the in the winter months, however BC may be a little milder than the rest of the GWN? During some particularly cold winters I have switched to 10w40 in my daily but typically I do not and run VR1 year round in Philly. I do have high lift cams and stiffer valve springs in all but one of my other cars so for that reason plus the emissions exempt issue I wouldn't use anything else in them, however that's not the case with the truck. My knee jerk reaction to the high mileage was to fill the truck with VR1 when I bought it, but after joining this site and learning of others' experiences with the T4 I went with that. As Extinct points out, there are also detergent properties in it which should be beneficial with regard to preexisting sludge and it seems to exceed the zinc and phosphorus requirements, possibly to a fault, but I don't hear many people on here complaining about emissions problems. I do think the benefits of thicker oil really come into play with higher mileage engines and worn tolerances however, so while I may not switch to 20w50 at 175k, maybe at 200k I'll be more inclined. By then cats shouldn't be important to me either. API rating is another equally important piece of all this that should be considered as well but I haven't found much info that says we're making a mistake with the oils being discussed.

 

@ahab They dropped emissions testing here a few year a few years back. A lot of the good hot rod oils are no go because of the Cat issue you mentioned, kills them very short order. My part of BC rarely gets very cold, but 20/50 is just to much for Oct through March and I do get out in the hills where is much colder.

I have a few more weeks of iffy weather then I will switch to a heaiver oil and post the results, I think it is worth running the test after a good long drive too just to check the difference, as you noted oil temps are higher after driving under load and make sure I have decent pressure at idle.

 

Update at 200ish I am right around 15-12 PSI at idle, so 10/30 is a little light for my Disco, I think 20/50 will be overkill, AMSOIL makes a good 10/40 with good zinc levels (1378 ish) so that will be my upgrade. The hottest I have have reached is 215 on a long slow up hill climb in 104F temps so that should give me a good cushion and it has a pretty good thermal rating.

@ahab have you ever checked you Disco oil temp? I have no cooler, but I could put one in.

 

I don't have a cooler either, but no I haven't checked my temps. Where are you picking them up, oil pan? Now that you've got me thinking on it, I can put in a DPST switch to cycle between oil and water temp on my gauge so it should be pretty simple to retrofit. Added to the list ...

 

@ahab I have a glowshift adaptor at the filter, I have a second port so I could add a temp gauge. I am just not sure how critical it is, if my engine temps are under control then the oil temp should be within 230 deg F normal range.