BMW does not manufacture their parts nor fluids.


That is relabeled Liqui Moly diesel additive - https://www.amazon.com/Liqui-Moly-20.../dp/B002PE95ZA

When my wife had her TDI, I did notice a quieter, smoother running engine, and about 1-2mpg average more per tank, when I used Opti Lube XPD formula (all season) when we lived in the North

I just ordered about 6 tanks worth of XPD, and the nice people at Opti Lube are sending me some samples, of their Summer+Cetane (2 tanks worth of doses) - XL Lubricant formula (2 tanks worth), and Boost (2 tanks worth)

I am going to run the following tests and share my results but be advised it may take a while, we only drive about 350 miles per month on average LOL (both of us work from home)

Will reset trip and calculations each tank when I fill up, I am going to try out:
-Summer+ with XL (50/50 dose)
-XL with Boost
-XPD only

I don't get much more than freezing temps so I am not *as* concerned about anti-gel here in the South, but I do believe that we still get winter diesel blend, which I'll have to confirm. XL and Summer+ do have some water dispersents and deposit additives (Summer has more deposit additives, while XL has more water demulsifier) - XPD has more water demulsifier than XL, and the same deposit additive as Summer, PLUS it has anti-gel -

XPD is by far the most to use per tank, along with their Winter formula (for you extreme northerners with cold temps-

I can't imagine I would **need** XPD in the winter, considering the vehicle is garage kept and if we get more than a week of temps below freezing, it's a statewide travesty. Hoping the XL/Summer+ will be my ticket.


The HFRR rating on the XL formula and the XPD is astounding, and that is the number I am most concerned about - lubricity for the fuel pump - bottom chart on their website -
http://opti-lube.com/

Linked from the Optilube website is this study..

If lubricity for your fuel pump is your main concern, it seems to indicate that the XPD is a much better better product for this than their Summer+ (XL product was not in this test)..

The XL and the Summer+ seem to have different objectives. The XL having the best lubricity increase rating, and the Summer+ having better Cetane improvements. Confused, where you planning to 'mix' the two?

Curious to hear the results of your testing, but you need to drive more!

The Spicer test is a little old and outdated and yes it got Opti-Lube on the map but they have done some other testing since then -(but yes its usually the first thing you find)


FAQ on the products page is very helpful
Diesel Fuel Improver FAQ - FAQ

They talk about mixing, for example the XL is really a deposit and lubricant only, not much cetane additive, but the Boost is basically just cetane improver - so mixing the two at their lower ratios should really give a nice result.

Summer+ is basically the summer formula of XPD, without the Anti-Gel, and with more cetane boost additive (their Summer and Winter formulas are directly marketed at Power Service with the silver/white bottles)

XPD is the "all in one" which you can use in all temps depending on dosage (more XPD has more anti-gel) but if you live in frigid temps, Winter is better for that, because the cost is prohibitive on XPD when using "double dose" in winter

Read the treatment rates on each product page and calculate which additive makes more sense for your tank, again in MD you may get some temp dropping in winter so maybe Summer+, and keep a bottle of XPD handy when the temps dip?

Wear test done with XPD and XL, from Intertek labs:
http://opti-lube.com/downloads/intertektesting.pdf


Basically XL at the standard rate will lubricate as well or maybe a touch better than XPD at the standard rate. And its more cost effective if you aren't as worried about wanting cetane boost, or needing anti-gel additive.



And an interesting test, gasoline mistakenly added to diesel, very shocking considering the "oops" moments we've heard of -
http://opti-lube.com/downloads/Opti-...DieselTest.pdf

In regards to mixing, since its so cost effective, I was going to either run the Standard treatment rate of XL (2 oz per 20 gallons, which is what I use for our tank, close enough to capacity), and the Premium rate of Summer+ (another 2 oz, 1 oz per 10 gallons), and will give me all I want, plus the cetane boost, just without the Anti-Gel.


Alternatively, was thinking about doing the Premium XL rate (4-5 oz per 20 gallons), with the Premium treatment of Boost (2 oz per 20 gallons), for max lubrication and cetane.

Although accordingly to Opti-Lube's chart, the Summer plus has a *touch* more deposit control, however I'm thinking at the premium XL dosing, it should be a moot point. Summer+ really is the best of both worlds in the freezing temps though if you analyze the chart, and cost per dose.


I really don't think I have a *need* to use XPD year round because of my temps, standard rate is about 5-6 oz per tank, and in cold weather it needs to be doubled to 10-12 oz - Whereas I could use 2 oz of XL and 2 oz of Summer (or 2 oz of Boost and 2 oz of XL) and it will go a lot farther per tank.



http://opti-lube.com/images/home/OL_...RFtable_F4.jpg

I was considering trying a mix of the XL (for lubricity) and the Boost (for Cetane)..

Gotta get this stupid EGR control stuck open issue figured out first though..

It definitely would be better than straight diesel - not a bad mix! You can buy a quart of each on their website and one of their empty pint bottles (it has a window on the side) and just mix 2 oz of each and dump in at fill up), a quart of each will be good for 16 tanks if you're doing it 1:1 ratio -

FYI for those that may be interested..

So I had mentioned the Southern States 'Super Gold' Diesel fuel product in the first post of this thread. I emailed them for more details, the response is below..

My understanding is that the Engine Manufacturers associations recommended a wear rating of 460 or below, but the US standard for Diesel fuel wear rating is 520 (and for Cetane is 40, though some states are higher).

So between the Cetane rating, and the Lubricity rating, it does, at least, seem to be a step above the 'standard' for diesel fuels in the US..

Southern States Rep reply below..


"Good Afternoon Scott,

In response to your inquire on our Supergold 50 diesel, the cetane rating is 50, and its lubricity rating based on ASTM D6079 testing is HFRR below 460mm.

I hope that this answers your spec questions. Thank you for your inquiry.

Best Regards,

Bob Conrad
Commercial Sales Representative
Petroleum Division
Southern States Cooperative, Inc."

That is good to know - a nice product out of the pump for sure!

Any feedback on your testing?

I hate to bring an old post back from the dead, but I have 128k/mi on my x5 35d bummer and it's the best truck I've ever owned. However, purchased in california as a CPO, had outstanding highway mileage (28.6mpg avg combined daily) during its first 2 years here. Moved to idaho for 2 years after that and saw the same fuel consumption. Moved back to California and the entire drove down from Idaho, held a solid 29.9mpg avg. Now that I've been in cali for about 3 months, I can't get the average above 22.1mpg and I work far from home, no traffic. Questioning the fuel quality and the political agenda now because diesel is frowned upon in cali. Is it the fuel? Or has something worn out? My x5 drives the same, it just takes a ton more fuel for the same throttle response. I always used dieselkleen to bump numbers but now even with the additive I'm falling short at 80mph holding 20mpg. I use Rotella t6 5w40 full synthetic no additives the entire life of the truck. Considered CBU as an issue, but boroscoped my intake to find not a single bit of oil caked in the flaps. I'm stumped. Somebody please let me know am I dealing with an ultimate failure, or has fuel been allowed to fall below the threshold of acceptable? I've been overdosing my fuel lately and seeing a slight increase in performance and economy, but at the cost of boost and soot. It's been regenerating every 150 miles since I moved back and it used to only regen every 450-500 miles its whole life. Same oil. Same everything. Nothing has changed except the fuel at the pump. I need more cetane right? How much can I dose it before it detonates? Why is california diesel so terrible? I use AdBlue from the factory and all my services are 4500 miles oil, 20k trans and diffs with motorkote every change over the last 100k miles. It's not the motorkote, I know that. But lately it idles really loud, chatters like a 7.3 off the line and boost rolls in heavy like I'm asking for too much load just to accelerate. I'm super confused. I'm afraid to bump the numbers any higher on cetane and nothing else is wrong with the truck. I've replaced everything including suspension regularly and tires don't wear uneven or anything. Just a sudden decrease in throttle and economy. It sees 112 miles daily and regens either to work or from it daily. EGT and boost is always normal, intake temp is always 30+ ambient air which is normal for heat soak on the turbos. Can't figure out why it's always regenerating now without any codes, all gauges normal, low coolant Temps around 175F at all speeds which was normal since new. Only changed tires once, brake pads and oils. Control arms and alignment were necessary at around 70k miles. Didn't have the issue until I got back to California. It has to be the fuel, but why hurt the diesel owners? Our trucks are cleaner than gassers when running right like mine is.

@famousX5 (and experts here) what is your running temp? Is it possible your thermostat is bad? I remember reading that the thermostat going out can cause the lower mpg,wondering if it could have to do with the regeneration thing as well.
Curious myself as I don't generally get more than 22.1 combined, right on the cusp of lower mpg and my running temps were right on the lower end of normal expected as well - it has been months since they checked, sorry don't recall my actual temps).