97supratt

There’s no way to prevent carbon in an engine, I don’t care what you’re reading.

Techron is badass, it’s used by premier engine builders. I’ve used it when I put together motors I’ve built in the past.

Charles Navarro

In all the years we've tracked 987.2 engines, we've never seen any buildup in the intakes, however there are contributing factors to buildup. An engine that is tracked sees lots of high rpm use with high port velocity. We've also run Driven XP9 in all of them that holds it's viscosity better than street oils (doesn't vapor off). The oil is also changed after every event.

On a street car with extended oil change intervals, fuel dilution contributes to a loss of viscosity, which increases the amount of oil consumption. The thinner the oil gets, the more ends up back in the intake via the air/oil separator. All that can be done to minimize this is running the oil level a little lower in the engine (not filled to the max), using an oil with a higher HTHS viscosity (M1 0w40 barely comes in a a 40 wt), and change the oil more often. Starting with an oil with a higher HTHS viscosity with a shorter OCI will reduce the effect of fuel dilution common to GDI engines.

When regards to fuel additives, they won't clean the intake port buildup, but depending on injector placement, it can help with some valve cleaning. What is important is that the fuel additive being used uses polyetheramines (PEA). That's the most effective fuel system cleaner you can use.

Manufacturers are indeed now going back to mixed port/direct injection, port for low engine speeds and direct injection for high engine speeds, both for port cleaning and also improved efficiency.

SConn

Mr Navarro,

Thank you for your insight. Can you elaborate a bit more on running a lower oil level in street cars in order to maintain higher viscosity? It seems like lower levels would thin more quickly than higher levels, taking into consideration the product being used is already less susceptible to fuel thinnage.
This is very interesting...

Jack F

Any opinions on using BG 44K? Would this be any better than Techron?

Charles Navarro

Running the oil lower does nothing to help with oil thinning. What it does is reduce the amount of crankcase windage and lowers the amount of oil laden air the AOS has to handle from the crankcase.

SConn

OK, still confused... Sorry! And don't feel like you have to explain of you don't want to, but wouldn't having less oil in the reservoir mean more air?

rnl

don't know about it's effect on carbon build up, it's great for my daughter's Honda fuel system, cleans it right up, smooths the idle for thousands of miles

Homeles

Yup, we used this method in the 70’s

jimmymoO

This is interesting. I tend to time it to run down my gas right before the oil change. After the oil change I refill the gas with the Techron. The belief behind this the oil is fresh with the treated gas. Then again, what do I know.. just going by what I thought it makes most sense..

Charles Navarro

The engine has a wet sump. Like with most wet sump engines, running the oil level closer to the minimum oil level, especially on track, reduces the amount of windage in the crankcase.

Since the AOS puts a vacuum on the crankcase, oil laden air is sucked out of the crankcase into the AOS. Theoretically, all the oil gets separated, but it doesn't. Some of that oil makes it's way into the intake and is consumed by the engine, leading to deposits in the intake.

SConn

Thank you for that wonderful explanation! All the pieces came together for me with that! I appreciate your knowledge and time!

polobai

Wouldn't a properly plumbed catch can/air-oil separator help with this also?

Charles Navarro

Nope. The stock AOS works very well. Eliminating the AOS and operating the crankcase at ambient air pressure would reduce ring seal as the rings are low tension and require the application of vacuum to them for optimal sealing.

Sir Ducer

Thanks Charles, I'm the 2nd owner of this car and that's what I've seen on the valves after 115k km by the previous owner. in this case, I would assume that its because of all his daily driving activities, instead of hard driving on the track.

So for the owner who does mostly daily driving, and the occasional track day, would you say that some form of cleaning is required, and if so, is walnut blasting preferable over other methods?

Charles Navarro

It would seem that walnut shell blasting is the industry standard for corrective action. I would imagine daily driven vehicles, especially those run with M1 0w40 and long drain intervals, will be most susceptible.