That's one hell of an article. I'm gonna read over it in more detailed this evening but damn. It is just completely crazy and goes against everything. I was running royal purple 5w-20 hmx because of the added zinc and the fact it has added detergents for high mileage vehicles. I will say I run it in my work car and i can get actual 15k oil change intervals (following their guideline of doing the first 2 oil changes at the manufacturers guideline to get all the crud out) and I love it in my car. Hell I was getting it off of amazon in the 5 gal jug for under $150. I'm just not a fan of the low 0 weight oils since it's made for engines with tight tolerances and we all know our engines don't have "tight" tolerances

 

I can agree with that. My 04 seems to run smoother with the 15W-40 vs the 5W-40 that I run in the "winter" months here in GA. I am coming up on an oil change and was thinking of going back to 15W-40 and just running that year round.

Also seem to think I had less oil drips on the driveway with 15W-40 but that might just be my imagination and/or another leak to be found on my engine.

Still leaves me pondering what oil to use since his data seems to throw out a lot of our closely held oil assumptions for our Rovers.

 

The main Indy LR shop here uses nothing but Swepco 20w50!!!

He's seen a whole lot more engines from the inside out than I and he doesn't use thin oil.

I'm not ready to be sold on any of this yet.

I lost a cam shaft running Castrol 5w30 which a dealer put in there while under warrantee.

I think I will keep listening to my engine and not the interwebs... till I see something from Bob the oil guy anyway.

 

I switched to Rotella in the Rover because it cleaned the engine and thicker oil quieted the racket. It also seemed to slow the leaks and definitely improved the pressure. I've changed Engines since I started using it.

Now I read that pressure is bogus, to a point, and that the detergents can actually ruin compression in our Engines, and that the heavier oil creates heat and shortens the life of the engine. Wow.

After my post above, I was also thinking about my diesel engine and Googled something like "can you use gasoline engine oil in a diesel engine.". That produces pages and pages of results explaining why diesel oils should not be used in a gasoline engine, in detail. Not a single result addresses using gasoline engine oil in a diesel engine.

I am switching back to a gasoline oil next change. I know the engine will gunk up a little more (I've seen that) but that one negative seems far outweighed by the positives set forth in those articles and about a dozen more I read today. I'm just bracing myself for some massive leak somewhere when I do.

 

Well I'm still a firm believer in a heavier weight oil in our engines. I will still use a heavier weight oil at least a 10w-30 or 10w-40 in mine. I will use royal purple probably though. I know there isn't a lot of fans of it but the high mileage stuff is great for having a good zinc ratio (1000-1100ppm) and has great cleaning abilities and that's from first hand use not just from a lab standpoint. I won't use the racing stuff due to the high level of zinc and I know with our engines not having tight tolerances, we need a thicker oil. The light weights might have been fine when the engines were new but not after 16 years of use. That's just my 2 cents on the matter but I will never use anything less than a 10w in mine, synthetic or Dino just because of the tolerances. Hell you could replace every seal and switch to a 5 weight or even a 0 weight and still have leaks. I look at these engines like the old detroit diesels (screaming jimmies) if it ain't leaking, it ain't running right

 

The long story was 122 pages when printed to PDF. Mad it much easier reading but I will reserve my comments after wading through much of it.
......

 

If you read his articles all the way to the end, he doesn't just say use light weight oil in every engine you get your hands on, it says use the lightest oil that will still provide sufficient and acceptable oil pressure,,,, (we all know in Rover V8 with its lazy and stupid oil pump lightest weight that will provide acceptable oil pressure is w40, so that's what we will use anyway),, most of the talk about lightweight oil being better vs heavier oil is when your engine is designed for it, most modern engines use 5w30 or 5w20, and lately even newer engines are designed for 0w20 oils, because they have better oil pumps, & thats whah article suggests in more than a dozen paragraphs, "USE THINNEST OIL THAT CAN STILL PROVIDE ACCEPTABLE OIL PRESSURE",,, IT DOESNT SAY USE A THIN OIL WHEN YOUR OIL PUMP IS AS WEAK AS A ROVER V8 & distroy it,!!
But not to use a heavy oil in an engine that calls for lets say 5w30 or 5w20, because it will reduce the flow, & in many places he suggests to use a high flow oil pump if possible then switch to a Xw30 weight, and still says check oil pressure to make sure there is sufficant oil pressure, so you don't destroy the engine,!
If you read article all the way, (which is hard, because very long) it says wear capability of oil doesn't make much difference in crank & rod bearings AS LONG AS THERE IS SUFFICANT FLOW & PRESSURE, which is very accurate because you simply can't compress any liquid, so really there is no contact between crank & bearings as long as there is sufficant flow to overpower the amount of oil that is bleeding out of them, damage in bearing happen when it looses more oil than oilpump can pump in there,,,
So Wear protection of oil works mostly in areas like cylinder walls & point of contact between cam & valve train, where oil film & oil film alone need to make a barrier to reduce friction & wear,,
If you look at long list he made of testing different oils, (which by the way takes a lot of dedication & hard work) & compare different DIESEL oil's to each other, almost all the ones that have dual purpose (gas & Diesel engine use) are better than the ones that are for diesel use only, I think the reason is that when oil is in a gas engine it doesn't get any help from gasoline to lubricate cylinder walls (cause gas isn't a good lubricant) but diesel is a very good lubricant & it lubricates the cylinder walls as it's being sprayed by injectors helping the oil to provide better protection, also Diesel engines mostly don't have a very high lift & long duration cams as gas engines,,, That said, diesel oil in any case is a better detergent to be able to cleans dirty Diesel engine, because of very high compression of diesels & lots of blowby due to their high compression,, (around 20 to 1, compared to 8-10 to 1 for gas engines),,
As for leaking, of course any Dino oil will leak less than equal weight synthetic, because good synthetic will clean & find new places to leak that Dino couldn't,, so if your engine is leaking a lot already with Dino it will leak a lot more with synthetic,,,
Some will emphasis that a 0w40 or 5w40 is too thin compared to 15w40, but the fact is that they are only thinner at startup which is a good thing,, it's good to know a 0w40 oil is still much heavier in startup even in a very hot day, than a 15w40 is in normal operating temperature (which for oil is about 230*f or more),,,, & when they both reach operating temp's they are pretty much in same viscosity range, that's why last number in both says w40, (yes there is a range to qualify as 40 weight oil & some can be slightly on heavier or lighter side of the acceptable tolerance range, provided by SAE),,
(By the way 0w40 Mobil1 has 1100ppm phosphorus & 1000ppm zink which DOESNOT make it a low ZDDP oil),,
By end of day we all want best protection for our engines period, we all can read lots of diff articles, but at the end of day we will believe whatever we want & whatever we think sounds better to our ears, (& sometimes it's hard to accept what we thought was right isn't as correct as we thought it is,) but opinions are opinions, & facts are facts, I have read trough lots of diff articles about oil, from Bob the oil guy to jack the oil king, but honestly never seen any of them come up with any kind of real testing to see at what point an oil will actually fail to protect against wear but this 540rat, they all say I read here or heard from that guy or so & so said,,, non ever tested anything,,
At least this guy dedicated his time for many years to come up with some kind of real test data, & that has more value for me than just assumption,,

 

As I've mentioned before, I got a free new factory 4.6 at 40k miles as a replacement when it was discovered to have the misplaced front cover dowel issue leading to low oil pressure (in 2007.)

The dealer broke the new engine in with Castrol 5w30 synth.

burned a quart of oil per roughly 1000 miles since new. They said that would go away but it didn't.

Cam Shaft blew out two lobes at 85k (35k on new engine.) Not due to low oil levels. I was paying attention. Also at same time the oil pump gears were found to be broken.

This happened just after the extended warantee expired so I then switched to using reputable indy LR specific shops only, after a long search.

That's when I started learning about thicker oils with detergents in these engines and how to do some of my own work. I've seen the results long term just turning over 200k miles of mostly trouble free driving pleasure.

BTW still burns oil but the thicker the oil the less it burns. Sometimes I use 20w50 Swepco and the difference is notable.

 

I'll agree and say the guy knows his stuff and has spent a lot of time on the subject and it was nice to not have to cypher through all the scientific jargon but as you said, we all have our separate beliefs and thinks some kinds will work better than others. Just good to know that there is actually a source of a guy who went all out on ever part of it to do it right.

 

It's my pleasure sharing the article with you guys because you care and spare no trouble or cost getting things right. I have to say the results are a bit of an 'eye opener' to me also, I used Mobil 1 in my extremely high revving race engines because it was recommended by the powers of knowledge back then but maybe it wasn't so good. Another Kiwi racing pal reckons Valvoline was the dogs b------s and used it all the time.

I hope this article helps and can save you all some cash along the way.

PS. It's amazing the difference in brands between diesel and gas and also the online difference in prices which are often not substantiated and built on their old reputations not their current quality and technology.