I had issues with buildup on the control ring/vanes a few years back at around 96.7k, occasionally it would drop to limp mode with P1251 logged and actuator was stiff to move, usually only a problem on a particular stretch of road where it gets steep and you drop a gear, vanes go from open to closed and the it doesn't and can't make boost you feel the hesitation. I tried BG244 and it did nothing obvious for me other than increase mpg, I gave AR6400D a go at 108k.5, nothing obvious at all. 3 weeks later Costco opened up fuel on it's local site selling premium diesel for less than supermarket diesel at 110k, so I started running it and within a tank the problem was pretty much gone. I ran for two years with zero issues like that, but a change in driving pattern means I didn't drive past Costco for a few months and the RAV was relegated to tip runs and holiday use and fed supermarket fuel, 2,000 miles later the same problem occurs.
This time I listened to friends in the trade, grabbed two bottles of Forte TDC at £12.50 each from my local factor and as per the instructions added both to a full tank if you have had an issue - this gives you time to consider your lifestyle choices and the pro's/con's of 'I told you so' vs. not buying a new turbo fitting kit/oil changes/hours of your life on a Saturday afternoon splitting/cleaning/reassembling the turbo 😄 By this stage I had been able to drop it into limp mode more or less at will, sure enough after 15 miles it did just that. Obviously not a great start, but also too early to do any significant good. Within 50 miles it was back to 'normal', the hesitation that preceded limp mode was gone. By 150 miles it felt smoother to spool up the turbo and was pulling as well as it's ever done in the last 120k i've driven it. Having run the tank through to reserve, I shoved £10 of BP regular yesterday at 132.9 (ouch) and then necked it at Costco for 123.7 later that day, at 9.2p/ltr difference between Costco Premium and BP regular i'd rather drive the extra few miles to Costco and hopefully run without issue for another few years and save money. Trying to be objective, the BG244 is not marketed as a turbo cleaner, so my expectations were probably unrealistic, the AR6400D is, and at £33.11 for two bottles it's not exactly cheap and didn't do anything obvious, 2 bottles of Forte is £25 and did exactly what it said on the bottle within 50 miles, I know what i'd buy again.