Oil Sample Through Dipstick

[Pgh TT]

I have an Audi TT with the 1.8T engine. It is very difficult to take oil samples using the drain plug because of the cover that fits under the engine (has to be removed). In addition, Audi provides free oil changes so I am currently not changing the oil myself.

Recently I took a oil sample through the dipstick tube using a small diameter tube and a drill driven pump. I took the sample after running the engine at operating temperature; I let the engine cool off some to prevent melting the tubing / pump. I discarded the first volume I removed (about twice the sample bottle) before I filled the Blackstone sample bottle. This seemed to work OK although I had some trouble maintaining suction for the pump.

I have wondered if this technique will allow for taking a good sample? Was the loss of suction an indication that I was taking oil from the top surface of oil and would that result in any bad readings? My oil sample seemed OK after 10,000 mi except for high insolubles (~2%).

I plan on taking additional oil samples for this car in the future. If I use this same equipment to take another sample, should I try to clean out the tube / pump? If so, how? Any suggestions?

 

[Spector]

This is the way most people take a sample, well, the way I did for many years and some say better as you are not getting the bottom of the pan. Some analysis companies provide a syphon type bottle with a tube to perfrom exactly what you did. No problem with the analysis etc. Further, the first sample is fine as you are not getting it off of the bottom in all probability. I never went for a second fill of the bottle, too much of a hassle. I don't feel it ever made a difference. Yes, I reuse the tubing as well as I had to make one to fit smaller dipsticks and did not want to throw it away. Again, if any difference it is too small to measure IMO.

[ May 27, 2003, 03:45 PM: Message edited by: Spector ]

 

[Patman]

Is there anyone here who is willing to take a sample both ways? Draw one from the dipstick and then drain the oil and draw one there too. And then see if the lab shows identical results or not. It would be interesting to see!

 

[Jay]

You could use an $8 aquarium pump that allows you to attach a vacuum line and then drill two 1/4" diameter holes in the lid of a spare cap that fits your sample bottle. A section of 1/4" PVC tubing fits in the top of one hole and leads to the pump. The other section of tubing goes to the dipstick hole. The PVC tubing that fits in the lid only pokes through 1/4" or so. It doesn't touch the drawn sample. You "throttle" the fill rate by unscrewing the lid slightly as the bottle fills letting some air leak in.

The drawn sample never touches anything but the inside of the clean PVC tubing and the sample bottle. The aquarium pump never draws anything but air. Throw the dirty section of tubing away afterwards.

[ May 27, 2003, 08:54 PM: Message edited by: Jay ]

 

[3 Mad Ponchos]

Patman, the problem with your idea is that you won't get identical results even if you use the SAME method, so any differences can't necessarily be attributed to the sampling method.

See my "margins of error" page for an example; the two samples were collected back to back. They are close but they do vary somewhat. It would have to be a pretty huge difference to show up as something attributable to the method of collection.

Cheers, 3MP

 

[Pgh TT]

Thanks for the infor. BTW I also emailed Blackstone Labs; they said using the dipstick as I did was a good method. Also said I could reuse the tubing / pump if I cleaned it out with kerosene to ensure a clean sample next time.

 

[labman]

Compare the length of your suction tube to the dipstick. It it goes past the oil line on the dipstick, it should be below the surface of the oil

 

[rob-the-oil-nut]

quote:

---

Originally posted by Patman:
Is there anyone here who is willing to take a sample both ways? Draw one from the dipstick and then drain the oil and draw one there too. And then see if the lab shows identical results or not. It would be interesting to see!

---

I do hereby volunteer. 3 Mad Ponchos makes a valid point but it is still worth doing and posting. Keep in mind I am planning on doing this when I change the oil, that could be October or later (I want the max cold temp performance of fresh RedLine for the super cold times) That's a ways away, I could forget or be poor at the time.

 

[Al]

They sell a sample pump at Amsoil-why not contact on of the sponsors. Another option is to contact Oil Analysts and they provide a sample bottle that acts like a suction bottle. You can then reuse it. One problem I noticed with my son's GrandAm-the hose got stuck at the bottom of the tube. It just won't work.

 

[Weezz]

Mity Vac makes a fluid transfer pump (about 10-12 bucks-Sears carries them)and it comes with several adapters, one of which is a hose to fit down into the oil dip stick hole. I bought one for my differential oil change and it worked great, it fully disassembles for clean up. If you clean it after each sample this may be a good way to draw your oil samples.

Hope this helps.

 

[BOBISTHEOILGUY]

Under this article section I have pictures of different methods of taking oil samples. You might find it interesting on the various methods. Also, I use a plastic aquarium tube from wall mart, 50ft for 2.99? anyway, no reuse, cut, use, throw away.

http://theoildrop.server101.com/cgi/ultimatebb.cgi?ubb=get_topic;f=4;t=000082

 

[rob-the-oil-nut]

Just wanted to add that I bought a Blackstone pump months ago, and used it for the first time yesterday. The worst think I could possibly say is that I got a few drops on the pavement. It went really, really well, beyond expectation.

 

[jason07-1zzfe]

How much is the Blackstone pump? I don't see any reference to it on their website.