What is an "HFRR" number and why does it matter?

At Opti-Lube we speak to some who are unaware of what an HFRR number is. On the home page of Opti-Lube.com you can see our performance table where this number is posted for each of our blends.

Well, what is an HFRR number and why does it matter?

Many have recognized the importance of having high lubrication in the fuel they use in their vehicle, because poor lubrication in the fuel has been linked to premature wear of pumps and injectors.


Take a look at these 2 links for further info on Lubricity:




We occasionally speak with uninformed diesel owners who say “My vehicle is designed to run on today's pump fuel”. Is that really the case? Would you also use just any motor oil available just because your vehicle will run on it?

HFRR (high frequency reciprocating rig) is recognized as the standard testing machine used to measure diesel fuel's lubricity by the ASTM (American Society of Testing and Materials). The number corresponds to the width of the wear scar (in microns) where the two pieces of metal contact while being submerged in the test fuel. In this case, it is a ball bearing that wears on a plate or disc under a standard test load. This is why the smaller the number is desired. The less the wear scar or scrape width, the better lubrication of the fuel. As you can imagine, this is done under some very specific parameters in order to make sure the test is as consistent as possible. Even heat and humidity are controlled during this test. The resulting number or scar is examined under a microscope in order to do the measurements.

Since this is the standard recognized test for fuel lubricity, we thought it would be a great idea to have our own testing setup in order to be able to adjust mixes for the best results. We checked into pricing for our own HFRR testing machine and found the cost to be over $40,000. A little rich for our needs! Contracting our tests out of shop became a great option because of this high cost. We wanted to share with our customer’s the results of these tests to give valuable information when deciding on a lubrication additives.

It is still surprising to us here at Opti-Lube how many refer to the 'Spicer' test (named after Arlen Spicer) even years after this test was conducted. Many have found Opti-Lube because they came across this test while researching fuel additives and wanted to try it out in their diesel. As far as we know, this was the last and only fully independent test done on multiple additives at one time.

Full Report Link:


Spicer Test Results Graph

Will an independent 'Spicer' test ever be repeated? Probably not. Also, some of the additives found on the 'Spicer' test did so poorly, that the producers would never agree to participating again. Our guess is it would need to be a test funded outside any participation by the additive producers to be a reality. The costs and time involved are just to great for anyone truly independent.

With this in mind, here at Opti-Lube we are compiling an HFRR test of as many of the major blends of additives as we can. While this test may not be independent, we hope the reader will be confident we did not 'adjust' anything and provided honest results. Look for this test to be published in the coming weeks. 

Leave a Reply