Pros: Small, sleek design, cheap, works most of the time
Cons: Doesn't work all the time, tests need to be repeated
I’m not sure where I first heard about Oilyzer, but it must have been bobistheoilguy.com (BITOG) forum where the hard core lubrication oil geeks reside. I’m guilty myself of being a long time member and like most of the BITOG crowd, I obsess about motor oils, try to use best oils, and spend a lot of time (and money) trying to determine the best oil change intervals (OCI) as more is not necessarily better. I sent a few used oil samples for oil analysis on my cars.
But first, what is Oilyzer? It’s a new (as far as I can determine) gismo sold online by oilyzer.com. It’s marketed to car owners who want to optimize OCI based on objective info, but who are not willing to pay for oil analysis ($10-30 a test or more), as it is often more expensive that oil change itself.
Here comes The Oilyzer, $20 simple, small, and sleek device (actually, $30 with S&H, but comes with a bonus tire pressure gauge) that promises checking oil for signs of wear and contamination and will signal with 7 green, 2 yellow, and 1 red lights how much life oil still has. The website’s FAQ do not specify what light should be the threshold for oil change and delegates that determination to the users. I suspect most people will wait for the last, red light, but I believe that would be a mistake and oil should be changed earlier (first yellow light in most cases), but more about it later.
This is not the first time similar devices (dielectric coefficient meters) were marketed for similar purpose. I only found it in retrospect when I researched the issue. They were never popular and time will tell if Oilyzer will succeed.
As I mentioned above, Oilyzer determines dielectric properties of oil, even though the specifics are not disclosed and patent is pending. There are many other similar patents on this technology and anyone interested can look them up. So, the area is well researched and the concept is fairly mainstream. Even Mercedes uses dielectric oil sensors as part of their onboard oil life determination system.
Basically, it works like this. Air has dielectric coefficient (DC) of close to 1. Mineral oils have DC of slightly more than 2. Formulated engine oil has DC slightly higher than mineral oil due to additives. Oxidized oil has higher DC than fresh oil. Carbon has DC of 3. Water has DC of 80 (room temp). Metals have infinitely high DC. If oil oxidizes with use, gets contaminated with water or wear metals, the DC increases. So, this is how it works. But there are also problems. Gasoline has DC of 2 (lower than engine oil). High-end synthetic oils that are ester based have higher DC. Some of oil additives may also raise DC more than expected. This explains why this method cannot be reliable when oil is contaminated by gasoline or when special or high-end oils are used.
Now, how Oilyser is operated. The oil selector is selected (synthetic or standard) and device is turned on with no oil on the sensor. It takes a few second to calibrate the sensor (using air as constant). The device will signal ready state by blinking green and red light. Then oil sample is placed on the sensor. It only takes a few drops, but some dipsticks do not carry enough oil and it takes a number of attempts to cover the sensor with oil (my 03 corolla is the worst and it takes 10 times). Then test button is pressed and in a few seconds one of the LED lights blinks. One of the 7 green, 2 yellow, or 1 red. The position of light should correspond to quality of oil (ot lack thereof), green LED #1 being hopefully fresh oil and red LED #10 being hopefully spent oil. The device will signal unusually high DC by fast blinking red, meaning a major engine fault (water or lots of metals). To test another sample (or to retest, a must in my experience), the device is turned off and the sensor is cleaned dry. The sequence repeats for the next test.
Why repeat tests are necessary? Well, I noticed that not every test result makes sense. Sometimes fresh oil would measure high or used oil would measure #1. I think problem is with cleanness of the sensor during the calibration and test phases. If it is not clean enough, it will mess the measurements. I determined that at least 3 tests are necessary. One of those tests (most commonly the first) is usually an outlier and the other 2 agree and can be trusted. Rarely, I had 4 measurements that were close but different, I would average them and trust them. On the other hand, I had results when there were multiple different results all over the scale and that was a sign that such specific oil cannot be measured by Oilyser. Fortunately, I had only one engine oil in my collection that did that.
I said oil collection as I managed to stock 14 different fresh motor oils (not counting various ATF and gear oils) to have my cars and a boat well oiled and I managed to keep used oils for the last 3 years (too lazy to dispose promptly, I guess). I also have partially used oils inside cars and the boat of course.
It took some time to finish the testing to arrive at conclusions and here they are:
1. Most fresh engine oils tested #1, making the Oilyzer’s scale feasible for oil monitoring. The exceptions were: #3 for heavy duty and marine 15W40 oils, #3 for synthetic Maxlife 10W30, and #2 for Maxlife 5W30 and Mobil 1 0W40. These higher reading corresponded to higher additive levels and/or possibly esters in the formulations. One oil could not be measured at all and threw inconsistent, but high readings. It was QS torque power full synthetic 10W30. I’m not sure if it uses exotic additives or contains mostly esters.
2. The results of used oil from my corolla made a lot of sense. When I tested my multiple used oil samples from corolla (5000 miles/6 months) they almost all tested #6 (well in the green zone). The 5000 miles/6 months is the Toyota’s recommended OCI. I earlier confirmed by my oil analysis that 5000 miles was the limit for the older API: SL/ILSAC GF-3 mineral oils in this car that saw lots of city driving punctuated by hwy driving loaded in hot climate. While the wear metal numbers were low, 10W30 oil would thicken to 40 weight due to oxidation. The newer oils (now, API: SM/ILSAC GF-4 is the current oil rating in USA) have improved oxidation resistance and thus, longer intervals are feasible in this car. The oilyser’s reading of only #6 agrees with that. I would continue to use oil up to #8 reading (yellow LED) in this application.
3. Gasoline contamination does indeed affect the readings. When I come back from a long road trip in my RAV4, oil tested #4 after 2,400 miles of mostly hwy driving. 100 miles of short trip city driving later, reading went down to #3, most likely due to gasoline dilution. Thus, oil should be tested only after a hwy trip after gasoline contamination is eliminated (but testing should not be done on hot oil as DC is temp dependent and readings will not be reliable). It’s also hard to interpret readings from my boat that is carbureted, sees low hrs of use, and idles a lot (dock maneuvers). The samples after year of service read #4-#5. While this sounds like little oil deterioration as the marine oil starts at #3, they probably were underestimated due to gasoline contamination.
4. I tried testing of ATF and gear oils, but results were all over the scale and apparently, additives or formulations in those fluids are incompatible with Oilyzer.
This device is not approved for diesel use. I can imagine that the high load of soot in diesel oil requires different scale.
Bottom line: I found this device useful but not without it’s quirks. This can be useful for people who want to tweak OCI without the cost of used oil analysis. If one uses a typical oil and there is no fuel dilution, this gismo works. However, one needs to be patient with it, follow the instructions literally, and not be afraid to repeat tests when results make no sense. I would also advise to test fresh oil first to put used oil results in perspective.