Hey all, have NOT had a LT4 in yet, but have had a few 2015 LT1's and we are seeing very little oil burping from the dry sump when run mid cross hatch!!! The improvement in the drysump tank appears to be working much better than the 2014. What is still alarming is the intake manifold is still getting saturated. We had in a 2015 with just over a 1000 miles on it, and the airbridge was dry...almost no oil at all, but the intake manifold was saturated with it. We did video as they bridge has changed a bit from the 2014 so we have both videos and we removed the TB to get into as much of the bottom of the IM as possible. The good news is the dry sump did NOT show burping!!!
I'm assuming Tracy was talking about the 2015's equipped Vette's with dry sumps that didn't have any kind of catch can system installed. In a separate thread a detailed description was provided on improvements GM made that addressed the oil burping issue made to the dry sump tank for 2015, and Tracy posted he was impressed with the improvement made. However, nothing was done addressing the introduction of oil (ingestion) through the PCV system, or at least that's how I understood it... Just reading allot and trying to understand based on logical thought from previous experience on this stuff. Could be wrong here, but it kinda makes sense to me..... All these oil ingestion issues weren't all that relevant prior to "Direct Injection" because any introduction of oil was diluted or washed down with the fuel being introduced into the intake tract prior to reaching the intake valves. It's existed for decades but wasn't as much of a problem if any.... Now it is because there's no fuel to mask it. My guess is the clean side separators may not be as relevant now with the improvements GM made to the tanks, but what the heck, why not go ahead and install it anyway as a back-up..........and Rx has a dropout can for that so that it won't go to the IM?
While it is very true the fuel system cleaners will not keep the intake valves clean, there are some that are beneficial for injectors, fuel level rheostats, fuel pumps, etc. If using gasoline without ethanol, it is beneficial to periodically use an additive to remove water, expecially in cooler climates or downright frigid like it is here this week.I saw a guy today pour a bottle of fuel injector cleaner in his new Silverado, and I thought about what are CRC, Seafoam, BG, etc. going to do now that those treatments have zero effect on anything in the fuel system now with DI....these companies will have to find a new product set now.
A additive for freezing would your correct, but the rest of the fuel system is now coated against any corrosion, and the DI fuel injectors operating at 2,000-3,000 PSI seem to keep all varnish and deposits "pressure washed" so we have yet to see any clogging in the past 8 years of DI. We have seen a few failed injectors....but no clogging like old port injectors were prone to over time. Nothing in the fuel pump can benefit, but you are dead on that ethanol will sponge water into the system. Todays fuel systems have no parts uncoated anymore as far as the corrosion related issues from Ethanol....(I still hate the stuff.....corn is for far better things than a fuel supplement!) In the early fuel systems ethanol would attack the fuel level rheostats, look back at the C5 for plenty of example of that.While it is very true the fuel system cleaners will not keep the intake valves clean, there are some that are beneficial for injectors, fuel level rheostats, fuel pumps, etc. If using gasoline without ethanol, it is beneficial to periodically use an additive to remove water, expecially in cooler climates or downright frigid like it is here this week.
And yet there are tens of thousands of cars on the road with direct injection that are running just fine by different OEMs. Porsche switched to direct injection in all of their models in 2009 or 2010 without adding any supplemental catch cans todate. Perhaps in spite of the apparent build up on the back of the valves these engines still run strong. As with any accessory or insurance it is an option for each individual to decide whether they need, want or pass on it.I am very interested to see how this thread continues to develop. I've seen the intake valves on a 335i that was direct injected and I could not believe the amount of buildup on the back of the valves and stems.......the car had less than 15k miles on it and I couldn't believe it would even run with that much carbon build up. I've had fears of direct injection ever since I saw it. I'd strap a HEPA filter on my car if I thought it would prevent it.