I'm sure this has been discussed before, but not recently, and it's usually as a side-note on some other thread. I posted on this a while back on another thread and the response was, to say the least - hostile. It was so much fun, that I thought I'd try again, and give it it's own thread!

This is about using heavier-weight, higher Zinc-Phosphate oil in your modern Mini (or not), and why or why not you should do so.

Before you comment on this thread, I ask that you first read these two articles. (But feel free to add to the list of reading material!)

http://www.machinerylubrication.com/...?articleid=518

http://www.enginebuildermag.com/Arti..._got_zinc.aspx

There really are two issues here: oil weight, and Zinc-Phosphate additive. For purposes of argument, let's leave the synthetic/mineral aspect out of it.

When I was ready for my first oil change (at 3,000 miles - a mistake - should have been 500...) I took my 2008 Clubman into my BMW mechanic that I've used for years. (I sold him my 250,000 mile 1995 325is - part of the deal was two oil changes...). He insisted that I use the same 20W50 Kendall mineral oil he'd been using in my 325.

I was skeptical, citing the same warranty and "the manufacturer knows what they are doing" arguments I have seen put forth here in the past. He then showed me a rogue's gallery of worn parts off of customer cars that had used the BMW-recommended oil, saying that these things haven't occurred when customers have used his recommended oil. Keep in mind that BMWs recommendations have changed over the years, and they are now using the same thin, low Zinc-Phosphate oils that the Mini division is using. So, my mechanic has witnessed the changes over the years as cars have come through his shop.

I did some research, and finally conceded. To hedge my bets, though, I ordered a mixed cased of Brad Penn 20W50 and 10W40. Brad Penn uses a blend of synthetic and mineral oils. So, I've got a blend of a blend. (I went to the trouble of calling the factory, and confirming that it was perfectly OK to blend the different grades.) My mechanic thought I was nuts to water-down the 20W50, but I slept a bit easier. I figured, maybe there was SOMETHING this this wise old goat didn't know.

BTW, when he finally did the oil change, he pointed out two things that scared the bejeebers out of me: (1) the metal filings in the drained oil (2) the scoring already visible on the cam roller bearings. (On current minis, at least the S engine, the bearings are clearly visible with a flashlight when you remove the oil filler cap.) Wish I'd have done that oil change at 500 miles. (Better yet, immediately after driving off the lot, and THEN at 500 miles.)

After reading the articles above (and others) here's my take:

- The EPA has pressured manufacturers and oil companies toward thinner oils, because this slightly improves gas mileage. But, referencing the first article, this may actually DECREASE mileage over the total life of the vehicle. It is a short-sighted strategy.

- The EPA has also pressured for lower Zinc-Phosphate levels, because Zinc-Phosphase MAY contribute to deterioration of catalytic converters. Because the industry was unable to come up with a meaningful test, they've set arbitrarily-low levels. As well, the EPA has insisted on unreasonably-long warranties on converters, making it very difficult for manufacturers to build ones that won't wear out during the warranty period. And so, we are now sacrificing engine life for the sake of the catalytic converter!

- With synthetic oils (oh, sorry, I forgot I wasn't going to bring this up!) and with Zinc Phosphate now almost a non-issue, manufacturers can increase the recommended oil change interval, lowering (on paper) total cost of ownership, and reducing their cost for "all inclusive" service warranties. (One reason for short oil change intervals is that additives become "used up". The most important additive we are talking about here is Zinc Phosphate. If you haven't much of it to begin with, what to worry if it's level drops to zero?) BTW, I have had my oil tested by a lab in the past (but haven't done so yet with the Mini.) This testing confirmed that between 3,000 and 5,000 miles, the additives are done.

- This is one case where manufacturers are more than willing to comply with the EPA. Can you see why? They have an interest in your car lasting through the warranty period (all-inclusive warranties today) but not much longer.

In my research, I have not come up with ANYTHING suggesting that modern engine designs require lower-weight oil than past engines, or low levels of Zinc Phosphate, or that modern engines run on heavier weight oil or higher Zinc Phosphate will mis-perform or wear out faster. I have searched in vain for any such evidence. In fact, all the evidence I have found suggests the opposite.

Let's have a rational discussion of this. Please don't point out that running oil not recommended by the manufacturer may void the warranty. I know that. My own take is that BMW would be unlikely to disclaim a warranty based on type of oil use, except on a catalytic converter replacement. Disclaiming engine warranty claims on this basis would open a hornet's nest.

Here's what I'd LIKE to see: specific (SPECIFIC!) engineering or scientific reasons why modern engines (and, more specifically, those used in Minis) require thin oil and/or low levels of Zinc Phosphate for better function (other than a small increase in gas mileage) or longer life. Evidence that using thicker oils or higher levels of Zinc Phosphate will in some way damage these engines. Other, engine-related, non-warranty considerations why these thin, low Zinc Phosphate oils should be used. I'd like to see this backed-up by citations by industry experts. Let's not cite "because the manufacturer says so" because I've already heard that one. (However, I'd love to hear "the manufacturer says so, because of...")

I have an open mind and am willing to change my viewpoint. But, if I am wrong, obviously, my research efforts have been flawed. Help me find the reasons why I am wrong.

 

Well, I don't think that there are any design reasons why modern engines need lower levels of ZDP (zinc diphosphate) to operate correctly. I think the problem is with the catalytic converters. There's really no debate that ZDP poisons catalytic converters, and as you said, the manufacturers have to warrant the catalytic converters for a very long time, so low-ZDP oils make sense.

Also, ZDP is an extreme-pressure additive. As such, it only comes into play when the oil film has failed to keep the moving parts separated and there's metal-to-metal contact. As long as you're not overheating your engine or going too long between oil changes, I'm not convinced that the presence/absence of particular levels of ZDP actually affects the long-term wear on the engine parts.

 

Oops! I see I posted this on the wrong forum! I'd meant to post it on the "SECOND generation Stock Problems/Issues" forum! Mods, can you move it?

(On the other hand, I'm likely to get more sympathy here. )

 

If you click on the little red triangle at the top-right of any of the posts, you can ask the mods to move the thread.

 

At 8k miles on my R53 using Royal Purple, still plenty of additive effectiveness, but down on viscosity. I've not seen scoring on the camshaft or rollers and analysis does not show elevated wear metals.

I have not read the articles as you requested. I would hope you would at the very least perform a baseline analysis and a minimum of one treatment analysis as it is you who should provide some first hand empirical evidence.

 

Great to hear that you aren't seeing the scoring. But, then again, you aren't using the manufacturer-supplied or recommended oil. I did, for the first 3,000 miles. :( The dealer would have me do my first oil change at 15,000 miles. When did you switch to Royal Purple?

What weight are you using? And which Royal Purple product? Are you using one of the consumer API-spec oils, or XPR (which is high-ZDDP like mine) What weight and class was specified for your year? Is your oil within the manufacturer's spec?

FWIW, I'm using Brad Penn Penn-Grade 1 Partial Synthetic High Performance Oil. (I use a blend of 10W40 and 20W-50).

Royal Purple is expensive stuff. REALLY expensive stuff. Even the API-spec oil is $10/quart. XPR is $13.50 in case lots on EBay. I pay $5 for the Brad Penn. Royal Purple is great if you are willing to spend it. I did run RedLine in my BMW for a time, and that is the oil that I tested. (See below). I'd be happy to run Royal Purple XPR and change it at 5-6K, but it's way more costly than what I am using and still technically voids the warranty.

I'm curious, would you change your oil at the manufacturer-recommended interval? My onboard computer is indicating my FIRST oil change at about 15,000 miles. Would you go out that far?

Will do that and report back. Though I'm not willing to do it with the 5w30 low-ZDDP stuff. I've been meaning to test at 0, 1000, 2000, 3000 and you've given me the incentive to do so. I recall coming across a place that does "packages" of tests for a good price.

I only did two tests on the BMW. I could only find one of them just now.

One was done in July 98 with Redline 20W50 with 3800 miles on the oil. It tested at SAE 40, and a comment from the lab (Analysts, Inc.) indicated "with secondary 1 micron oil filter oil will go 10K. This oil will probably go 5K or maybe 6K." Zinc was at 1456ppm Phophorus at 1376 and moly at 807 so a mea cupla there. Of course, that's twice as much ZDDP than in FRESH oil recommended by BMW today! (And about what is to be found in the oil I am currently using fresh.) Total solids 0.1%, TBN 8.02 (new 12.0).

 

And 15,000 is just what your OBC is recommending *now*. Depending on your driving habits, that may get stretched out to 20k miles or even more before it actually "comes due". My OBC-recommended services so far have come due at 12,500 miles and 33,200 miles (almost 21k interval). I'm at 50k now, and it looks like the third service isn't going to come due until about 53k, so that's another 20k mile interval. (I haven't gone that long between changes, though - I've been changing the oil at 10k intervals, which is about the longest I'm comfortable with based on the oil analyses I've had done.

 

If you want a good synthetic oil with extra zinc phosphate, you might want to
consider Mobil Delvac 1 5W40. It's usually thought of an oil for diesel engines,
but it also works well in gasoline engines.

http://www.mobil.com/USA-English/Lub..._ESP_5W-40.asp

 

Jtara, I read both articles.

The first makes a well reasoned case for using a slightly heavier oil grade, 10w30 or 15w40. It warns, however, that this may adversely affect mileage, could be an issue in cold weather, and may possibly void your warranty.

The second discusses lubrication issues with custom-built racing engines, and specifically states that heavier oils, or more additives, are not needed for modern OHC engines.

Neither convinced me to switch from the MINI owner's manual recommended oil grades.