First off, an annual oil service is not enough. No matter what the Mfr states, the engines that we see that live see an oil service every 6 months, despite mileage.
Secondly, you won't see benefits on your first service and sample of DT40. You may even see a UOA that's worse than you'd had before, this is especially true if you do not shorten the first service interval after swapping oils. Why? Cross pollination from what oil was left in your sump, heads, chain wells and etc that may imbalance the anti- wear and dispersant packages of the oil that you have swapped to.
Any time we change oils, especially to something with a composition of DT40 we will always do a flush oil with Joe Gibbs BR for 100 miles before going to DT40. This helps to purge the system and get a better initial result, faster.
If you don't do a flush oil you can expect to see the effects of this for a few services to follow. This is especially true since you went a whole year with the cross pollinated oil.
I have been seeing these types of effects since 2002, when we began hardcore oil development and analysis. Since 2006 we've been working with Joe Gibbs and developed DT40 together. The things I am telling you come from direct experience and carrying out almost 300 UOA last year alone.
That said, DT40 was developed around a 6 month service interval, and I mandate that the oil in my engines not go over 5,000 miles. Will the oil last longer than this? Yes! The difference is the amount of impurities that can be removed from the engine from more frequent services.
You can't expect to see benefits of the DT40 at this time, considering no flush was done, you had been running another oil for so long, and that you went twice as long on this first service. Oil isn't magical, it can't make an old engine new again, and it takes time to see the true results.
Flavor 987S, I'd like to review your UOA with Lake Speed. Please email to
jake@rabyenginedevelopment.com
There's more to UOA than wear metals. If your engine is seeming to like the heavier viscosity that you swapped to, I want to see if there's a reason for that. I see some engines that follow this same trait, especially 3 chain engines, as the vane cell adjusters on the intake cams have proven to at times have internal oil volume losses, which increases the engine's desire for a heavier grade oil.
All that said, European catalytic converters are not impacted by zinc like Asian or domestic cats. I have ran oils with as much as 2750ppm Zn without issues. I don't even worry about cats at all anymore.