Removing Engine Sludge
*HARD*
Generally, if the oil is changed regularly with a high quality detergent oil, there is no sludge buildup, and the engine does not consume oil, it should not be necessary to add any aftermarket cleaning additives to your engine oil.
Use with extreme care oil additives or treatments that are meant to clean internal engine parts. This is especially true with older cars. These separate cleaners, which are mixed with the old oil before an oil change in order to clean out "gunk" and sludge, contain petroleum distillates. While the concentrated chemicals can remove stubborn sludge, varnish, gum, carbon and other deposits, they also dissolve false seals in high mileage engines. These false seals are made of combustion byproducts and are useful at closing the gaps between highly worn cylinder parts. With the artificial seals dissolved, oil will then be burned by the engine, causing oil consumption to increase. A new engine that has been well maintained with frequent oil changes should not require separate oil treatments either.
However, if sludge buildup is confirmed during the oil change, the engine must be cleaned as soon as possible to prevent wear and engine damage. Remove sludge from your engine as follows:
- After dirty oil has been drained from the engine in accordance with oil change procedures, remove the oil pan and valve cover(s). If these parts are stuck, tap them lightly with a rubber mallet to dislodge them. Do not pry them loose; the sealing surfaces may become bent and leak later.
- Remove any old gasket material from the engine, oil pan, or valve cover(s). Use a chemical solvent to remove the gasket material. Scrape the oil sludge from the inside surface of these parts with a putty knife.
- Remove the oil pump from underneath the engine and flush it with solvent to remove any internal sludge. Reattach the oil pump.
- Clean the oil pan and valve covers in solvent. Install them back onto the engine using appropriate new gaskets and sealant. Tighten the bolts to the vehicle manufacturer's recommended specifications.
- Install a new oil filter and fill engine with SAE 5W-30 oil and one can of oil additive that has a strong engine cleaner.
- Put the vehicle through normal use but change the oil and filter after 100 miles. Change the oil and filter again filter after driving another 1,000 miles using SAE 5W-30 oil (with no additional cleaning additive).
- Resume regular oil and filter change intervals.