~Taking a Proper Engine Oil Sample for Analysis

PATH: REFITTING & REPAIR » DIY » Propulsion » Engines » Lubrication » Oil » Analysis »

^ Sampling an engine that cannot be run and warmed up
^ Sampling with a Sampling Probe
^ Sampling by Vacuum Extraction
^ ^ Instructions #1~#3
>>> ONLY Current Academy Members may view the rest of this page which includes:
^ ^ Instructions #4~#12, PLUS Important Notes, & MORE!
^ Documentation: Catalogs, Brochures, SpecSheets, Manuals, Parts Lists. Recalls, etc.
^ Forum Posts, Tech Notes & Tech Tips.
^ Publications & Media: Articles, Books, Magazines, Videos, Websites, Authors, etc.
^ Related EAB Webpages.
^ Visit our FEATURED ARTICLES Home Page! Thanks to our amazing contributors.
^ This Months Top 20 Most Popular Articles on our EAB Website.
^ Members must SIGN IN to gain access to Members Only areas of this website.
^ Become an Academy Member and gain access to additional pages and programs!
^ Comments for everyone to view: Submit to Comments@EverythingAboutBoats.org.
^ Academy Members’ Comments & Reviews that only current Academy Members can view.
^ Academy Members’ Exclusive Comment Submission Box.
NOTES: This page is pretty much complete. Please let us know if anything needs fixing. Enjoy.

It is always best to take the oil sample from a warmed up engine, so the oil is thoroughly mixed and everything in the oil, especially contaminants, are evenly “in suspension”.

In the event that the engine cannot be run for some reason, then the entire oil sump must be drained into a perfectly clean container and the entire container of used oil will have to be processed so the sample will be more representative (usually at an additional cost to stir up the contents and draw the sample), but unfortunately, far too often the analysis readings will be skewed enough to be misleading. Yet, this may prove useful in determining if a serious problem exists such as fuel dilution of the oil due to a leaky injector or fuel pump, or coolant contamination from a “blown” head gasket. Go to Engine Oil Analysis for a full interpretation of oil analysis results.

0606st_oil_change_03_z_oil_drainedThis oil was undoubtedly contaminated by the oil filter!

Taking samples from either the drain stream, the waste oil container, or the used filter is the least desirable method of obtaining an engine oil sample, as doing so more often then not results in an unrepresentative sample. The used oil filter usually contains high concentrations of contaminants that will throw off the analysis. The waste oil container may already be contaminated or it can easily become contaminated by falling debris. Then there is the sampling of the drain stream. In the early days of oil analysis, it was believed that a good sample could be “caught mid-stream” as the oil was draining from the oil sump (on most engines the oil pan acts as the sump). The sample was caught, not at the beginning of the draining and not near the end, but mid-way between (mid-stream, like at the doctors office). It was quickly realized however that a sample from the drain stream often contained high concentrations of contaminants from the bottom of the sump and the drain plug hole surroundings, (e.g. metal from the threads, etc), so better methods of taking a sample had to be developed.

Oil Sampling Probe

The most preferred method of taking an engine oil sample is with an oil sampling probe. If the engine is not equipped with an oil sampling probe valve, one can usually be installed. The valve is available from most large engine dealers. The probe valve allows a probe to be inserted while the engine is running, and the engine’s own oil pump will pump oil through the probe into the sample bottle. Just remember to reinstall the probe valve cap to keep the valve clean for the next sampling.

This sampling method requires a Brass Probe (like a Cat # 8T9208) and approximately 15 cm (6 in) of tubing (like Cat # 6K0713 or 5P6442 bulk cut to length). Some sample kits may already come with a disposable probe and tubing.

The process of taking an oil sample by an oil sampling probe is as follows:

1 – After the engine you are going to sample has been started and has been running long enough for the engine to warm up. set the engine at low idle and remove the dust cap from the oil sampling probe valve on the engine.


2 – Insert the probe into the valve and collect about 100 ml (4 fl oz) of oil into a small waste container. This will clean the valve and helps ensure a representative sample. Dispose of the waste oil properly. If the oil flow is slow at low idle, it may be necessary to have someone accelerate the engine to a higher idle while clearing the valve and extracting the sample.


3 – Insert the probe into the valve again and this time fill the sample bottle to the proper level (usually one-half to three-quarters full). Do not fill to the top. Do not allow any dirt to enter the bottle or contaminate the inside of the bottle’s cap.


4 – Withdraw the probe from the valve and secure the sample bottle cap tightly. otherwise, it can make a real mess inside the shipping cylinder. Make sure that the sample bottle’s outside is clean and place the bottle with the completed label into the shipping cylinder.


5 – Don’t forget to reinstall the probe valve dust cap.


From MacAllister Machinery

Vacuum Extraction

Vacuum Extraction is the most recommended method of taking an oil sample if the engine is not equipped with an oil sampling probe valve. With vacuum extraction, a length of clean plastic tubing is inserted into the oil sump (usually down the dipstick hole) about half way into the oil and the oil is drawn up the tube into the sample bottle by the vacuum created in the bottle by a hand operated vacuum pump. The equipment needed include the vacuum pump, a sample bottle, a length of sterile extraction tubing, and a clean tubing cutter. These items are readily available from many sources including most engine dealers, engine service shops, and oil analysis laboratories. Some engines (like Hino 4 & 6 cylinder diesels) require a smaller (3/16″ O.D.) diameter tubing to fit into their smaller I.D. dipstick tube. This smaller tubing is often stocked at local hardware stores or can be ordered. The hand vacuum pump’s knurled tubing sealing nut usually has no problem compressing the tubing sealing “O” ring enough to seal the smaller diameter tubing into the vacuum pump. Always store the vacuum pump, the clean new extraction tubing, and the tubing cutter, each in a clean place such as in heavy clean Zip-Lock type storage/freezer bags.

NOTE: You may want to wear mechanics gloves or surgical gloves (as shown below) to protect your hands and facilitate cleanup afterwards.

The process of taking an oil sample by Vacuum Extraction is as follows:

1 – Ensure that the engine has been properly warmed up, so the oil is thoroughly mixed and everything in the oil, especially contaminants, are “in suspension”.

2 – Cut about a half-inch of tubing off the loose end of the new tubing roll with a clean cutter to rid the tubing of any contamination that may have drifted inside the end. The roll of sterile extraction tubing should be stored in a clean Zip-Lock type bag until needed.

3 – Mark the new tubing to the length of the dipstick (tip to seal). This mark will be used later when inserting the tubing through the engine’s dipstick hole into the engine’s oil sump to reach the proper depth in the oil.

ONLY Current Academy Members
may view the rest of this page which includes:

4 – From this mark add enough tubing to reach the …
5 – Insert the tubing into the …
6 – Remove the lid from the …
7 – Insert the extraction tubing into the …
8 – Hold the pump upright and slowly …
9 – It is usually …
10 – Unscrew the …
11 – Withdraw the used …
12 – Store the …
A Note: You may wish to …
Another Note: Wearing clean …
An Important Note: If the pump requires internal cleaning,…
A Very Important Note: Never use the same vacuum pump for extracting …
^  Brochures.
^  Service Bulletins.
^  Training Videos.
^  Articles.
^  Websites.
^  Videos
Related EAB Articles:
^  Engine Oil Fundamentals
^  ^  Engine Oil Analysis

 and view the rest of this page.

If your membership has expired, CLICK HERE to Sign In and Renew.

CLICK HERE to become a member and gain access to
the rest of this article by reloading this page, PLUS
gain access to additional pages and programs!

to see examples of our website's comprehensive contents!

Thanks to our amazing contributors for the steady flow of articles, and to our dedicated all-volunteer staff who sort, polish and format them, everyday we get a little bit closer to our goal of
Everything About Boats. If you would like to submit an article,
see Submitting Articles.


Ford Industrial Power Products Diesel Engines
How to Identify Ford Diesel Engines
Ford 2715E
Lehman Mfg. Co.
Detroit Diesel 8.2
Universal Atomic 4
Chrysler & Force Outboards
Eska Outboard Motors
Perkins Engines
ZF Friedrichshafen AG
Allison Transmission
American Marine Ltd (Grand Banks)
Boat Inspection
Types of Marine Surveys
Marine Surveyors by Regions
Boat Builders By MIC
Beta Marine
American Boat and Yacht Counsel (ABYC)
USCG NVIC 07-95 Guidance on Inspection, Repair and Maintenance of Wooden Hulls

What our nonprofit Anchors Aweigh Academy and its
EverythingAboutBoats.org website have accomplished so far.

  • Published over 300 website main topic webpages, many with full articles on the topic. See our Website Contents in the Right Sidebar for the listing of the main topic pages.
  • Published over 9,000 marine vendor webpages, all with their contact information, most with a description of their products and services, many with product documentation, specifications and independent reviews. (Includes: Boat designers, boat building tools, material and equipment manufacturers and suppliers, boat builders and dealers, yacht brokers, marine surveyors, boat insurers, boat transporters, skippers and crews, boatyards and marinas, yacht clubs, boat rentals and yacht charters, boating, seamanship and maritime schools, marine law attorneys and expert witnesses, boat refitters and repairers, book authors and publishers, and video producers)
  • Acquired over 120,000 pages of product documentation including Catalogs, Brochures, SpecSheets, Pictures, Serial Number Guides, Installation Manuals, OpManuals, Parts Schematics, Parts Bulletins, Shop Manuals, Wiring Diagrams, Service Bulletins, and Recalls. And have made all viewable to academy members through the EAB website.
  • Acquired over 1,200 books and magazine back issues in our academy library and so far have made over 700 viewable to academy members through the EAB website.
  • Published over 500 DIY How-To articles about boat design, construction, inspection, operation, maintenance, troubleshooting and repair. We are working hard to do more.

We are currently formatting and polishing the Anchors Aweigh Academy online and hands-on courses. The Marine Surveying course has proven to be excellent for both the beginner and the seasoned surveyor, and especially helpful to the Do-It-Yourselfer.

Current Academy Members must SIGN IN to gain FULL access to this
website including expanded pages and valuable Academy programs
like our Academy Lending Library and our Ask-An-Expert Program!

If your membership has expired, CLICK HERE to Renew.

CLICK HERE to discover how you can become a Member and gain FULL access to
thousands of expanded pages and articles, and dozens of excellent programs

Thank you for your support. You make this website possible.

Comments for Public Viewing

Submit any comments for public viewing via email

Please remember to put this webpage's title in the subject line of your email.
All comments are moderated before they appear on this page. See Comment Rules.

FROM Donald: "This is an awesome website. I found the information that I needed right away from one of the over 10,000 free articles that you provide as a public service. I'm surprised that so much if this site is free. But I still signed up so I could access the thousands of expanded pages, interesting articles, and dozens of valuable programs! The member's library of books, magazines and videos that I can view online is really terrific! I understand that you and your staff are all unpaid volunteers. Please keep up the good work. And I commend you for your plans to add another 10,000 free informative articles over the next year. I'm thrilled to support you in this endeavor with my small membership donation. Thanks again for all your hard work."

FROM Huey: "I agree with my Uncle, I too have found the articles to be very enlightening. They say that it will take about 50,000 articles to cover the full scope that they have envisioned for the website. They have over 10,000 articles so far and that's doing pretty well, but it could take several years to get the rest. I also noticed that many of the Main Topic Pages and some of the article pages are still in the rough draft stage. I guess that they will fill in as they can get volunteers to work on them. But what I can't figure out is why anyone would spend the time writing informative in depth articles just to give away free to this website for publication? What's in it for them?"

FROM Dewey: "Well Huey, to me It looks like most of the articles on this website are written by very informed people, like boating instructors, boat designers, boat builders, riggers, electricians, fitters, marine repair technicians and marine surveyors. Writing such articles helps establish them as knowledgeable professionals. After all, this website was originally created by a school for marine technicians and marine surveyors. The website is growing in content every day. They even had to move to a bigger, more powerful server on October 15, 2018 because the website's traffic has been growing exponentially."

FROM Louie: "I agree with everyone above. This site is quickly becoming the ultimate reference resource about every aspect of boats and ships for everyone from the beginning recreational boater to the seasoned professional mariner. I use the topic pages on the right sidebar to browse around the website. It's like a Junior Woodchucks' Guidebook for Boaters. Their Members' Library of over 300 popular and obscure books and over 200 magazine back issues that can be viewed online is fabulous. The Academy's magazine is especially informative. On top of that, there is the "Ask-An-Expert program for members where you can get an expert's answer to any of your boat questions. And a whole years membership is only $25. What a deal! I really love being part of this "Everything About Boats" community and help provide thousands of helpful articles free to the public. I think that I'll sit down right now and write an article about my experiences boating with my uncle."

FROM Scrooge: "You rave about this website like it was the best thing since sliced bread. Well, I think it stinks. Sure, it has a lot of good information for boaters, and they're adding more every day, but it will probably never be finished. Furthermore, I don't even own a boat. And I wouldn't have a boat even if someone gave me one. Boats are a waste of money and time and energy and money! They're just a hole in the water you pour money into. If you gave me a boat, I'd sell it quicker then you could say Baggywrinkle. Then I'd lock up the cash with all my other money so I could keep my eye on it and count it every day. Bah humbug."

FROM Daisy: "I'm just so glad that Donald got the boat so we and the boys could enjoy boating — together. And of course all of the girls, April, May, and June, love to be on the water too, especially when that is where the boys are. Oh poor Scrooge, boating is more fun then you could possibly imagine."

FROM Scrooge: "After seeing how much fun you all have on the water together, I regret that I didn't have that much fun when I was young. I've had a change of heart, and I'm giving each of you a Lifetime Academy Membership."

FROM Editor: "For those of you that have stayed with us this far, Thanks. You inspire us to keep working on this labor of love. We know that we have a lot more to do. Ultimately, we hope that we can help you enjoy the wonder filled world of boating as much as we do. We are all waiting to see what you have to say about this webpage article. And we assure you, your corrections, updates, additions and suggestions are welcomed. Let's work together on this.