UOA after Switching from Mobil 1 to DT40

I have previously posted results from 2 UOA for my 2003 4s. Jake made reference to "liquid death" so i switched to Driven DT-40 and just got back my latest UOA. The DT40 oil change was done 1 month after the last Mobil1 oil change in February, so its possible the recent sample has some Mobil1 mixed in with the DT40. Still seem to be getting a bad Oxidation Value. I do drive the car hard after its warmed up, so maybe i just need to shorten the oil change interval from 5k miles to say 3k. Any thoughts? I also see Fuel Dilution in this sample but not in previous ones Thanks Marty

Hey Optionman - good to meet you under the shady trees last weekend ! I sent oil into blackstone for my first analysis ever. i like the color coding of this report, im waiting to see what comes back from blackstone. anyhow, hope to see you round soon again john

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I'm no oil analysis expert, but that looks pretty good to me...!

From what I understand, you will need a few UOA after a switch from a brand/type.

Mine took a couple of UOA before the Mobil1 or whatever the PO was using disappeared.

Sometimes I don’t understand everything I see in these reports. One thing that adds confusion is they don’t give units for each measurement. I assume that the wear related elements are ppm, but others are not so clear. For example, the oxidation values a higher number is a worse number ( more oxidation). When I look at report SDD-0186, the value of 40.6 rates a “red” ( outside normal range). Report AAA-1522 shows 42.7 (higher than the -0186 report), but only rates it a “yellow” (borderline). I also use Speediagnostix, and will send them another sample soon, but I think they can do a better job with explanations. I may give another service a try in the future.

If you have questions from a Speediagnostix UOA, just reply to the email with the analysis report. Lake will usually get back to you pretty quick as long as he's not traveling. I'm attaching mine after 2 changes of DT-40. I don't put a lot of miles on my car, but change the oil every 6 months. Our numbers look pretty similar other than your oxidation being higher.

Unless you performed a flush of the system as a short service interval, throw away the first UOA after swapping oils. Cross pollination occurs for the first 2-3 oil services after swapping oils, especially those that differ as much as DT40 and M1 do in every way. The clashing of the base oils, and additive packages is a huge issue when doing this, and they throw all the data off. these engines retain 1.5 quarts of oil within them when the oil is drained. This is held in the chain wells, and heat exchanger mostly. You simply can�t get it all out, it takes time and short service intervals to complete the purge. Don�t trust any of the data you�ve collected this far. People always want to see an instant success with the first UOA after swapping oils, And that never, ever happens... �Hey I swapped oils, so I am entitled to perfection now� Nope.

Thanks Jake. I knew there must have been a good amount of Mobil 1 left internally because my indy only used 8 of the 9 qts of DT40 i gave him. I will do a few more DT40 changes and continue to monitor UOA results.

This is why I recommend that someone do a 2nd oil change after driving 5 miles on the first oil change for cars that need to be restored (sat for years, abused/neglected cars, long overdue oil change, etc).

INMHO this is pretty much common for any petroleum/chemical product, grease/fuel/oils. Consistency is a good thing..