Trex101

Have you tried Redline Light Weight Shock Proof? If have and doesn't work then Redline D4 ATF (only ATF rated GL-4) maybe what you need to squeeze out of whatever remaining life from your GB.

IMO, 5w50 maybe too thick for your ride. Choose something thinner like M1 0w40 for day to day run about or 15w50 for exclusive track/race usage. oh, it's not true synthetic is too thin, that’s a myth. A SAE 40wt synthetic is exactly the same viscosity as a mineral 40wt oil, no difference at all.

Yes, RP maxgear 75w90 is purple in colour. According to the new SAE gear spec, the viscosity 21cSt @ 100'c should be rename as 75w110, RP 75w90 is thick.

Well, it's your money. Whatever makes you feel good.

What! $125 for 3.5L..... that's freaking expensive you got there. Do a search in ebay, you'll surprise how much cheaper you can get.

Do try to shy away from wide spread multi-grade oil like those 10w40 or worst 10w50 weight, most wide spread multi-grade oil had to use VII (polymer) to control the rate of thinning under increase temperature. These VII are the weakest link and will break down under heat or pressure thus forming carbon deposit & possible sludge. Clean engine Sludge engine

I would suggest GC 0w30 for both fuel economy gain & protection but do check for fuel dilution (UOA) if you are running rich AFR.

It's a Semi-Syn. Pls read above opinion. Motul 4100 10w40

Ok, a wide spread oil like 10w40 Semi-Syn are going to contain loads of VII (viscosity index improver), these VII polymer are weak in nature and will form deposit under high heat & shearing condition. That's not really a good ideal for a hot & fast spinning turbo, do we... That's why a good Synthetic (naturally multi-grade thus also eliminating the use of VII) with mostly group IV (PAO) or V (polyol ester) base oil will have a performance advantage over any Semi-Syn or mineral oil out there. Delvac 1 are rumors to be group IV/V blend while Mobil 1 0w40 are PAO/AN blend thus the value.

Delvac 1 is cheaper than 300V right?

Motul turbolite 10w40 is just a Semi-Syn oil, I would recommend at least a fully synthetic for turbo cleanliness and high temp protection. A wide spread 10w40 type semi-syn is not really a good idea for ring cleanliness i would think. Choose Mobil 0w40 or Delvac 5w40, whichever is cheaper. those are good oil at reasonable prices.

5w30 is good but do check your AFR if it's running rich or lean as too rich a AFR will increase fuel dilution in the oil thus making it thinner than 30wt.

You could run a bottle of SI-1, the injector cleaner might clean up dirty injector thus improve the spray pattern.

I have seen your UOA and doubt you will have an accurate reading unless after 3 OCI, ester base Redline has an aggressive cleaning abilities and it will show higher wear reading from the metal it displace. I would say save your UOA test till at less 30k later.

Can be found in Ebay. Castrol Syntec 0w30

Go for the Redline MT90 75w90 gear oil instead of the light weight shockproof. It will improved your notchy shifting.

Get the BKR6E-11 instead, that the better plug with V grove.

I would be easier if you have a picture of your plugs but from your description, it looks like it's a case of overheating. A number 6 NGK would have solve your overheating & possible hesitation problem.

It used to be true ambient temperature does plays a big part in old air cool engine but modern water cool engine oil temp just doesn't fluctuate that much be it in summer or winter condition. If you have an accurate after market oil temp gauge, you will find that the temp is pretty constant be it in 0'c or 50'c ambient. Motul 300v 10w40 cSt@40'c = 89.5 cSt@100'c = 14 VI = 161 Motul 300v 15w50 cSt@40'c = 128.1 cSt@100'c = 17.8 VI = 154 Actual oil temp directly affect the final viscosity, so depends on your avg oil temp and target viscosity needed. You can accurately choose your choice viscosity. Use the calculator to calculate the Vis at difference oil temp Viscosity Calculator

The correct way to gap a iridium. Iridium gapping

How does your plugs look now? If it looks white like the picture in the link, then you have overheated plugs. NGK If not, then gap down by tapping lightly to 0.9mm or lower (use feeler gauge to measure). See if it helps. Iridium plugs normally perform better then normal copper plugs due to hotter kernel flame & lower voltage required to jump the gap.

It will cause too much startup wear, once heated up to operating temp there's actually not much difference between a 30wt to a 50wt... For example let take a look at Mobil 1 0w30 when compare to Mobil 1 15w50EP. M1 0w30 cSt@40'c = 63.1 cSt@100'c = 11.0 M1 15w50EP cSt@40'c = 138 cSt@100'c = 18 So at 40'c ambient summer temp, during startup the 0w30 will flow 118% (74.9cSt thinner) faster then the 15w50 but at operating temp the 0w30 oil is only about 7cSt thinner then the 15w50.

Do a search in ebay on Redline oil. You be surprise what good deal you can find.

Change your PCV if you find alot of oil in your throttle body.

How much per quart and min qty required? any more details?