Best place to get used oil analysis done today?

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Feb 8, 2026
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Many years ago I used Blackstone for several used oil analyses, but that was over 10 years ago.

I'm thinking about making the switch from 0w20 to 5w30 in my Skyactiv Mazda based on recommendations from folks on this forum. However, I'd like to see how the oil is faring with respect to fuel dilution after a long interval (almost 12 months and about 7,000 miles) in order to form an educated opinion.

Is there a preferred vendor for these used oil analysis on my personal cars?
 
Polaris labs sold as Oil Analyzers through Amsoil. If you want to see the dilution it is a good choice as they use the approved ASTM gas chromatography (GC) test for that. It does need to fall 1 cSt below virgin viscosity for them to always do the GC test. Wearcheck is the other choice but they are more expensive and only do the gas chromatography if oil falls out of grade or you can pay an extra ~$10 to guarantee they do it.
 
Grab a 5qt jug of Pennzoil Ultra Platinum and get a free analysis kit from Polaris Labs. I am making the jump over from Wix to OA as mentioned above.
 
Polaris labs sold as Oil Analyzers through Amsoil. If you want to see the dilution it is a good choice as they use the approved ASTM gas chromatography (GC) test for that. It does need to fall 1 cSt below virgin viscosity for them to always do the GC test. Wearcheck is the other choice but they are more expensive and only do the gas chromatography if oil falls out of grade or you can pay an extra ~$10 to guarantee they do it.
What's the advantage of going through 2 additional middlemen when you can go direct to Polaris? I set up an account with them over the phone, I can view and upload samples through mobile apps and the prices for kits aren't bad at all.

The cost per kit for singles is slightly higher, but if you do like I do and order a 10pk, it's pretty reasonable.
 
Polaris labs sold as Oil Analyzers through Amsoil. If you want to see the dilution it is a good choice as they use the approved ASTM gas chromatography (GC) test for that. It does need to fall 1 cSt below virgin viscosity for them to always do the GC test. Wearcheck is the other choice but they are more expensive and only do the gas chromatography if oil falls out of grade or you can pay an extra ~$10 to guarantee they do it.
If you buy this sample kit through HPL/Advanced Lubrication, which uses Wearcheck, the kit is $35. You'll have to pay shipping to you and the sample to Wearcheck. They are really good people to deal with.

I've used Speediagnostix and Polaris Labs and had good experiences with Speediagnostix, but not so much with Polaris. Others really like Polaris. My preference for the money, and speaking with them, is Wearcheck.
 
What's the advantage of going through 2 additional middlemen when you can go direct to Polaris? I set up an account with them over the phone, I can view and upload samples through mobile apps and the prices for kits aren't bad at all.

The cost per kit for singles is slightly higher, but if you do like I do and order a 10pk, it's pretty reasonable.

Either way is the same product but the main advantage is cost like you say. I looked into a direct account at one point and found no reason to follow through on that. Living in Alaska, as I am, the shipping is an issue and the Oil Analyzers kits are pretty reasonable on shipping charges for delivery to me (seems to be $8 no matter how many kits I order at once). Prepaid UPS/FedEx/USPS for return shipping to the lab is only $10.60, which I couldn’t come close to if I had to ship on my own. If I lived in Indiana maybe it would make more sense to go direct.

I have also found that Amsoil customer service is a lot easier to deal with than calling Polaris directly, and the Amsoil phone/email rep seems to understand any request for additional testing I make unlike the folks I’ve talked to at Polaris. Of course I did shell out for the Amsoil membership so YMMV.
 
What's the advantage of going through 2 additional middlemen when you can go direct to Polaris? I set up an account with them over the phone, I can view and upload samples through mobile apps and the prices for kits aren't bad at all.

The cost per kit for singles is slightly higher, but if you do like I do and order a 10pk, it's pretty reasonable.
With my longtime Polaris account I'm seeing single basic testing for $31 and advanced testing for $43. At those rates its cheaper through Amsoil.
 
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What's the advantage of going through 2 additional middlemen when you can go direct to Polaris? I set up an account with them over the phone, I can view and upload samples through mobile apps and the prices for kits aren't bad at all.

The cost per kit for singles is slightly higher, but if you do like I do and order a 10pk, it's pretty reasonable.
I have both accounts as you suggested but it's been cheaper for me to order via Oil Analyzer. For bulk it may be cheaper but I'm sure many here aren't interested in investing that many at any given time.
 
Many years ago I used Blackstone for several used oil analyses, but that was over 10 years ago.

I'm thinking about making the switch from 0w20 to 5w30 in my Skyactiv Mazda based on recommendations from folks on this forum. However, I'd like to see how the oil is faring with respect to fuel dilution after a long interval (almost 12 months and about 7,000 miles) in order to form an educated opinion.

Is there a preferred vendor for these used oil analysis on my personal cars?
Polaris Labs. Indianapolis IN 317-808-3750
 
What's wrong with Blackstone? Still have a couple of their kits to use up. They were supplied free. If my memory serves me right, they were $40 the last time I used them. Have increased from $25 when I started using them.
 
What's wrong with Blackstone? Still have a couple of their kits to use up. They were supplied free. If my memory serves me right, they were $40 the last time I used them. Have increased from $25 when I started using them.

Blackstone doesn’t use an accurate test for fuel dilution. Since the original poster specifically wants to know about fuel dilution testing they are not a good choice. They use a flashpoint test to infer dilution which always seems to underestimate dilution severely.

In my opinion an ASTM D7593 or D3525 gas chromatography fuel dilution test is one of the most important pieces of in formation you can get from an oil analysis, and Blackstone doesn’t do it. They also don’t test for oxidation on their standard test which is also pretty nice to know. Add in the fact that they cost more and seem to be inconsistent on some tests such as viscosity, and many have concluded that Blackstone is a poor choice for used oil analysis.
 
What's wrong with Blackstone? Still have a couple of their kits to use up. They were supplied free. If my memory serves me right, they were $40 the last time I used them. Have increased from $25 when I started using them.
Check out response #12 here by @2.7ecoboostFordBronco. Polaris is one of the big boys in this oil analysis thing. They have all the proper certifications in their testing procedures and have labs worldwide. The problem is with Polaris is they ship out 10 packs. The last time I ordered from them I ordered 20 kits, the reason is the shipping from Indianapolis to Nebraska was ridiculously high, so I ordered extra kits to help justify the cost. You can order one kit at a time through Amsoil, who contracts to Polaris for their oil analysis. You have to spend the annual membership fee at Amsoil, however, to buy their products. Blackstone is convenient but with a poor way to test for fuel dilution, which is important these days. The newer engines are built from the factory to have blowby in their cylinders for the sake of getting a little fuel milage increase. With GDI fuel injection, part of the blowby is fuel getting into the engine oil, diluting the engine oil. Blackstone is better than nothing, however. @rstsco has a link going to HPL lubricants where can order a kit. They use Wearcheck. I have never used Wearcheck, but people like them. In my opinion, if you don't want to go direct through Polaris because of cost or the amount of kits they want you to buy would be to bite the bullet and join the Amsoil club. I think it cost about $20.00 a year for membership. You also have the "Motoroilgeek's" lab. (speeddiagnostix), which I thought was too pricy. I will post 2-3 links here to some labs you can look at.
https://www.speediagnostix.com/
https://polarislabs.com/
https://wearcheck.com/
https://www.alsglobal.com/en/oil-analysis
https://www.blackstone-labs.com/
https://www.oaitesting.com/
 
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I ordered a kit from Amsoil a month ago without having a membership. The no-shipping-included kit was about $26, and would have been about $22 if I'd had a membership. Delivered cost with tax was $28.74. The same kit from Polaris was listed at $43, before shipping.
 
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I ordered a kit from Amsoil a month ago without having a membership. The no-shipping-included kit was about $26, and would have been about $22 if I'd had a membership. Delivered cost with tax was around $30. The same kit from Polaris was listed at $43, before shipping.
What is amazing about that is the report you get back IS the same report as if you ordered directly from Polaris, since Polaris is doing it. I would have to assume maybe Amsoil is hoping to get you in their system, hoping you will get to looking around and order some of their high priced (but premium) lubricants. Either case, going through Amsoil is the cheaper way to get the same exact kit and lab as if you would order directly through Polaris. I didn't realize you could order the Oilanalyzer-Amsoil-Polaris kits from Amsoil without being a member. Thanks for the info.
 
What is amazing about that is the report you get back IS the same report as if you ordered directly from Polaris, since Polaris is doing it. I would have to assume maybe Amsoil is hoping to get you in their system, hoping you will get to looking around and order some of their high priced (but premium) lubricants. Either case, going through Amsoil is the cheaper way to get the same exact kit and lab as if you would order directly through Polaris. I didn't realize you could order the Oilanalyzer-Amsoil-Polaris kits from Amsoil without being a member. Thanks for the info.
Yes - It's a great deal all around. I did have a bit of a wrinkle in it not being obvious from the kit instructions how to set up an Oil Analyzers kit in the Horizon (ie Polaris) system when you already had a Polaris account, but a quick conversation with Customer Service got an "OilAna" sub-account set up in Horizon.

If your fine with an emailed PDF report they do that automatically.
 
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I ordered a kit from Amsoil a month ago without having a membership. The no-shipping-included kit was about $26, and would have been about $22 if I'd had a membership. Delivered cost with tax was $28.74. The same kit from Polaris was listed at $43, before shipping.
I just registered and did this for the $26 kit with no shipping.

But how do you get a "membership?" Do you have to pay for that?
 
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https://www.amsoil.com/offers/pc/?zo=515729

If all you order are UOA kits, it may depend on how many per year if it's worth it.

If you plan on ordering more, I personally will refund the $10 or $20
No worries! I probably won't do more than one per year. I drive very few miles and rarely change oil in either vehicle more than once every 9-10 months. Anyways I would like to do it on my Mazda because I'm about to hit 100k and want to decide which oil weight to use going forward.
 
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