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Decarbing engine

Is decarbing an engine really necessary? My dealer is saying that my 2007 Toyota Sienna (80K) should have it done. But I’m also reading online that it’s not really necessary, or that there are products that could do this for me? Any suggestions?

Pour a can of Seafoam Engine Tuneup in the gas tank at the next fill-up. If there’s any carbon deposits on the intake valves or in the combustion chambers, this product will remove them.


Unless you are having problems, it’s not necessary. Ask the dealer to show you in the owner’s manual where it’s needed. It’s not there. Buy Seafoam or a bottle of Techron from Walmart, if you want.

Unless you’re struggling with an operating problem, I recommend against the use of additives and feel emphatically that decarbonizing an engine is unnessesary on a modern engine.

Many years ago in the days of carburators, the '60s and before, engines ran very rich and relatively cool. The way to get more power was basically to dump in more gas. Carbon buidup in the engine as a byproduct of rich, cool running was common for engines that rarelty saw highway use. Carbon retains heat, great for charcoal briquettes but bad for engines. Carbon deposits could cause preignition. Decarbonizing was a common way of treating operating problems. One way of doing so was a hard run on the hhighway, often called an “Italian tuneup”.

Modern engines run dramatically leaner, hotter, and cleaner, and a properly running modern engine does not suffer carbon buildup and can operate for the entire lofe of the vehicle without ever needing decarbonizing.

That includes “induction cleaning”, which is removal of carbon deposits from the EGR system and the engine’s intake.

IMHO any dealer that recommends either is simply trying to clean out your wallet.

Unless you are having problems, no, it isn’t necessary. Your Toyota dealership is just trying to pad its profits.