Originally Posted By: OneEyeJack
There is someone that stopped by work that has a DI Mazda. We got into a discussion about oil because he uses Red Line like I do. We took a look at his valves with a borescope and at just over 100K there is discoloration and some rough looking areas but no built up deposits. He lives somewhere up in LA and uses Costco gasoline and adds Red Line gasoline treatment at their recommended intervals even though the gas is top tier. The whole car is in excellent condition and does not need the oil to be topped off between 10K oil changes. He said the level goes down about a sixteenth to an eighth of an inch on the dipstick before the next oil change. I wonder if the oil has something to do with the condition of the valves because I don't see how the additives in the gas or the additional gas treatment could get to the valves like it would without the DI. Red Line oil is a bit different than many of the more popular engine oils you can buy at places like Walmart or auto parts stores.
According to Philips, Red Line uses ester base stocks.
https://www.redlineoil.com/whyRedline.aspx
I believe that esters tend to have excellent high temp properties (like low NOACK loss), but relatively high cold viscosities...to my mind, Red Line could be a fine choice for warm climates and weekend racers, but maybe not for those who park their cars outside in cold climates. Note that Red Line was originally a racing lube company.
As for DI deposits, I tried spraying CRC GDI Intake Valve Cleaner in my open airbox past the MAF sensor while the car was idling and had a rather poor experience with it due to the physical configuration of my car...there was a 90 degree bend in the air path just past the sensor and the cleaner ended up fouling the MAF and, I think, pooling up somewhat before it got to the intake valves. I don't have before and after pics, but my car has actually been running quite well since I cleaned the fouled MAF sensor...I'll have to figure out a different way to introduce the product if I want to use it again.
The thing I always read about DI engines is that gas additives don't help with intake valve deposits because the fuel doesn't wash over the valves.