My 2015 RX350 runs very strong with the Ruthenium plugs. No complaints so far.

However, my old iridium plugs had about 190k miles on them when I changed them so not a fair comparison of the two plug types.

Good to know; a data point. My 2009 GS350 (was another immediately family member’s before, not mine since new) runs AMAZING with them at 185k miles. Runs and pulls like new, or better, in my estimation - just a incredibly “on” car that wants to run and pull (D4S is a big part of that, of course). My sample size is *1* which is not definitive, but it’s impressive.

NGK promises great results vs. Iridium w/them - and NGK is to be trusted in general. I haven’t run across many people who’ve started using them yet. But I have not run across anyone disappointed. Was curious when I saw it in your sig line.

I am putting new plugs in the 2RX next week, along with valve cover gaskets, pcv, radiator, t-stat - big service. But I did not spring for Ruthenium since it’s “only” a 3MZ-FE RX. Maybe I should have…

I am sure that the performance of the ruthenium plugs is only slightly better than the iridium plug. Probably like using an platinum plug vs. iridium plug in the same engine. Maybe a few extra horse power and MPG with the ruthenium plugs due to hotter spark, but not much that can be actually felt in the driver seat if both plugs types are freshly installed and compared back to back..

The main benefit may come from the service life as iridium works "properly" for 120k miles and the ruthenium plugs are rated for 150k miles before degrading.

You have come to this conclusion, vs the research done in laboratories, how? Just curious.

My butt dyno cannot tell the diff between plugs. but i do appreciate the extension in service life.

Lets be real.

I am just an ordinary person that does not have the time or resources to perform proper testing on spark plugs. My statement is all speculative and guess work at best.

What do the researchers in the laboratories that you are referring to state about the plug differences?

You can check the data at NGK’s website. It’s not imaginary.

I am sure that is not imaginary data, but considering that NGK is the one producing the ruthenium plugs that the data may have some bias or information that is more favorable to selling the company product.

I still will buy ruthenium spark plugs as that I do believe that it is an improvement over iridium plugs in performance and service life. However, I do not believe that the performance gain is much more than a few horsepower(if any) over the iridium plugs.

I'm not so sure having a pretty spark plugs will induce HP gains... The function of it is really on the name as making "Spark".

new contender in the WS space is AC delco. uber pricey fluid

It appears that AC Delco (part of General Motors) states the their WS ATF does not have compatibility with any other ATF. So it appears their WS ATF is not the same stuff as Toyota WS. Unless someone can find another reference that indicates it is compatible with Toyota WS.

https://parts.gmparts.com/product/ac...1G8vyfmylbpQZO

From AC Delco:
ACDelco WS-ATF (WS refers to World Standard) is a unique automatic transmission fluid that does not have compatibility with any other ATFs. With low viscosity at normal engine temperatures, this product has the potential to improve fuel economy.

I will just continue to use Idemitsu TLS-LV

The description was poorly written. There is only one fluid described as WS. What i hypothesize here is I doubt Toyota is actively licensing the WS license to anyone and hence no fluid but the dealer fluid can be granted the license. Same thing happens with older dex 3 fluids, GM stopped selling the license, and so basically all fluids use the language "meets or exceeds fluid requirements of dexron 3".

Regardless that price is crazy high per quart, rather just use dealer fluid if one is ok.

Or just use Valvoline Max Life transmission fluid. The stuff works well in Toyota transmissions and is affordable as it only cost about $25 for a gallon. No need to spend extra money for any other fluid WS fluid.

I am running Max Life in my 2015 RX350 transmission with over 190k miles and the transmission shifts buttery smooth.

I just ordered the Aisin stuff for my fluid change for my RX. To me this was a no brainer. Aisin is the manufacturer of the tranny, so it stands to reason they know how to make the best fluid for it. I used the Valvoline Max Life in my Tacoma for one of my fluid changes and it did not perform as well as the Toyota WS. I will not use anything but the Toyota or Aisin stuff moving forward. Yes, it cost a lot more, but worth it in my opinion.

What was the differences in performance with the Valvoline Max Life vs. Toyota WS?

Just curious.

My 10 year 190k mile transmission shift perfectly smooth with Max Life so I am wondering how much better should it be with OEM WS fluid?