Second hit on a 2 second, 2 term Google search of "tracer dye" compatible with "diesel oil" turns up a post from none other than this very forum, found in the archives, that speaks to both your questions about the O-Rings and the tracer dye:
TheDieselStop.Com Forums: oil in the valley
Here is the text copied and pasted, in case the archive links break:
Member # 5486 Reged: 02/20/00 Posts: 1433
Re: oil in the valley
#2218473 - 01/21/05 03:41 PM
I just posted this in a related thread, but a couple years from now, these threads will be no where near close to each other or related, and future folks searching for answers may find this thread over the other. Besides, I can't retierate the points below enough:
One fitting that hasn't been mentioned yet is the end plug
on the back of the HPOP. This is NOT the large cap cover retained with a tension ring (although that can LOOK like it is leaking).
It is the lone bolt head (serviced by an 18mm wrench size) that uses the exact same little O-rings that the two discharge fittings utilize.
This little end plug can vibrate loose. (Ask me how I know.) The end result appears as if the rear main seal has let go entirely, and the engine will pave the street with oil (and coat the entire bottom of the truck) at a loss rate of one gallon per 15 miles driven. And that is with this plug only less than 1/4 turn loose.
The leakage of this plug is nearly impossible to determine visually without being on top of the motor. Even then, the oil streams down invisibly, and the only indication given that a problem exists is a full valley of oil, the same valley that drains down the back of the block giving the illusion of a rear engine leak.
In my case, all of the oil rail fittings and plugs on the head (and on the HPOP) were bone dry. Yes, the Orange and Blue Charge Air Cooler hoses weep a tiny bit, but that little bit of seepage in no way accounted for the "Exxon Valdez" style puddles that I spent many more dollars cleaning up to be environmentally responsible than I spent on fixing the cause.
Speaking of fixing the cause, Ford has noted this problem, and has issued the following TSB's guiding dealer network service technicians to the fix (since more than a few rear main seals were misdiagnosed and replaced needlessly).
From Most Recent to Last:
I don't have the full text to these TSB's handy, but someone else here might post the text for all to read.
The Ford part number for the kit that contains three O-rings
along with a small capsule of LocTite 680 Sealant
Note that this kit is also available from International. The International part number for the Instruction Sheet is 1171794R2
You will also need a special tool to release the HPOP line fittings, unless you are lucky (as I was) and find that the line fittings are not leaking, only the end plug. Further on in this post, I will mention the CRITICAL first step that I took in making this determination, and what I believe to be the most ACCURATE method of locating and verifying leaks. But briefly back to those lines... if yours are in fact leaking, or for those that throw new parts at things before definitive diagnosis, the recommended tools are:
Rotunda Essential Tool #303-625
High Pressure Hose #6 quick release tool ZTSE4449
A $10. equivalent available at a local speed shop or decent parts house.
Now, back to the soapbox: before assuming that these HPOP fittings are the problem, STEP NUMBER ONE in diagnosing any engine leak nowadays involves the use of fluid compatible flourescent dyes that are responsive to UV/Blue or Black Light. Anything else is just a blindman's guess. Ford recommends and, in fact, now requires this step to be taken before paying on warranty work. But don't do it because "Ford says so." Do it because it makes brilliant sense. (And I mean "brilliant" literally, especially if you do the test at night!)
The Ford dealer sells the dye that is specifically compatible with diesel engine oil, but that dye may or may not have been obtained through Ford's distribution channels. Dealers buy those kinds of parts from other places as well, to save money. So you may get some all purpose stuff for $8.50 an ounce, and I'm the type that want's to know what I'm getting.
The one flouresecent dye that I am certain of that is A) compatible with diesel engine oil, and B) approved by Ford Motor Company (since 1994), is made by a division of Spectronics Corporation, the company that claims to have invented this diagnostic process, and that holds the most patents and sells the most products related to it.
Being approved by Ford is only an issue if your 5yr/100K mile warranty is still in effect, as the dye will stay in the motor until the oil is changed, and there is no legitmate need to change the oil after leak diagnosis and repair because after all, you just put in X amount of gallons to make up for the oil that was lost on the road, and to then make up for draining the HPOP to pull the plug and/or fittings to replace the seals. The dye is designed to remain in the crankcase, and if fact, you would want it to in order to monitor the success of your repair.
The company division is called Tracer Products, and the (Ford approved) product specifically formulated for diesel engines is their Dye-Lite TP3100. It comes in various quantities and sizes, so I recommend just picking up smallest case of six 1-oz bottles. The standard mixing ratio is 1 ounce per gallon of oil, so 3 oz will do nicely, leaving another batch for the future, or for a friend. Expect to pay around $25.00.
Now you ask, what about the UV light? TracerLine does sell a variety of UV/Lights, but you don't necessarily need to buy these (although they can be more convenient). I used several blacklights I had left over from a haunted house I constructed for the neighborhood kids, and they worked excellently. Blacklight flourescent bulbs and fixtures can be easily and inexpensively obtained at fish stores, and even Home Depot. You can buy the bulbs and use your existing fixtures if you like.
Some professional diagnostic UV lights (from Snap-On and Tracer) have the advantage of higher intensity for a smaller size, but remember that most technician work is done during the day time, so the UV light must compete with the ambient light. Since most DIY/ shadetree work is done in the evening or on the weekend, you have the advantage of working in darkness, which enhances the visibility of the flouresecence of the tracer dye.
I cannot reiterate enough (in fact, I'll post this in the related thread too) the importance of using tracer dye to locate the EXACT source of the leak, in order to fix just that problem... without unneccesarily futzing around with anything else that ain't broke. The dye will reveal that what looks like a leak to the naked eye isn't really the source. The key in seeing the differentiation is in noting the intensity of the UV reflectance.
A poster in the archives once complained of trying the dye, and claimed all he saw was flourescence everywhere. Yes, you will see that, but that is helpful too. You will know that the river of flourescence is new oil that just emerged from the engine, not residual oil left over in the valley. In fact, one secret to this is that you do NOT want to pre-clean the engine prior to diagnosing with the dye, because the residual oil remaining in the valley helps to dilute the intensity of the new flourescent tinted oil leaking from the source. In this manner, the differentiation can be observed.
I hope this helps you or someone else, as I would have wished for this amount of detail condensed into one post on a website like this when I experiened my oil leak. I had to slug it out on my own.
member Member # 18959 Reged: 01/11/02 Posts: 27
Re: oil in the valley
#2222684 - 01/23/05 11:23 PM
What Roybn said here about using the "Dye-Lite" product or something similar to detect oil leaks is right on the money. One thing though, if you are talking a Powerstroke watch the amount of dye used. My dealer used this product to attempt to detect an oil leak in my Powerstroke motor, but he had trouble detecting the leak as he only put 1 one ounce bottle in the crankcase, which is one-third the recommended amount. No wonder they had trouble detecting the leak. As I understand it a Powerstroke motor should have minimum 3 ounces of the product used (three one ounce bottles).