I have heavy engine sludge on my 09 g37. I was told changing the oil could blow a valve. 65000 miles on it. How can I fix? What's the best course of action?

buy an oil flush but before doing that get a scraper- parts washer brush and oil galley brush [looks like a rifle cleaning rod] and clean and remove as much crud from the heads ---best way would be to tear it down boil and parts clean it

check to see if you have a water leak into the sump
change over to diesel oil and change the oil filter every month for at least 6 months
diesel oil is the same as petrol engine oil but with a heavier detergent additive so it will clean out the sludge and deposit it in the filter

A full tune up ; plugs, wires cap and rotor ( if applicable,) air and fuel filter.

first you abuse the engine but cange the oil whit 15w40 i know is for diesel engine but that oil have quimical to clean engine and make two othrer oil changes every 500 milles and see what coin on good luck

#1 there are two types of oil used in engines asphalt base which leaves tar and sludge. And Paraffin base that leaves your wax sludge in engines. these are raw oils and additives have been added to create your engine oil. But now we need to determine how these deposit are created and stick to internal components and the damage that they have done. #1 oil has a life span created by time and temperature. So changing oil at earlier intervals helps stop these sludge build ups, Most new car manufactures call for a 6 month 7500 mile oil change. with a little* after it stating if you drive your short distances and in extremely cold weather to do it sooner. WHY? oil gets contaminated with the by product of combustion and the moisture content in the air by not building enough heat in the oil this allows the oil to cool and stick to the walls in the engine. now the other end salesman drive cars about 3000 miles a month go 6 months the same problem occur due to the additive package added to the oil base has been gone since the oil has reach its limit of use of 7500 miles so the contaminates are suspended in the oil to help create sludge. Now think of your engine having HIGH cholesterol changing your diet corrects this but in the engines case it is your to determine your driving style and change the oil accordingly. one change of recycle oil does not create sludge THIS is a long term problem, NOW CHEAP solution. Warm engine drain oil and filter install the very cheapest filter you can buy. put kerosene and cheap oil in crankcase with filter 3 quarts oil 2 quarts kerosene. let engine idle for 30 minutes. Drain out put fresh oil and filter. Drive 1000 miles repeat again this may take 6-7 changes to reduce the sludge. If engine smokes out exhaust after treatments check oil use which if greater than 1 quart per 1500 miles piston ring damage & valve guide have been done. A rebuild is the only answer to this problem. Good luck.

There are two main causes for sludge, not changing the oil and filter at regular times, and not running the engine long enough to get it hot.
You might want to get a second opinion from a shop other than the dealer. The dealer may have a sales promotion on engine flushes this month.

I doubt you have sludge in your engine since oil has detergent in it to prevent this. I would stay away from this dealer.

Oil changes based on mileage is the best in my opinion. I haven't heard of any sludge issues on this model. You can't believe everything just because it's written on the internet. Just follow what the owners manual calls for and you'll be okay.

Please change the oil now at the Nissan garage and watch the vehicle closely.

$100 is not so much like getting your car totally knocked.

Good luck and rate this solution/ suggestion.

The best way to solve the sludge problem is to drive the car! If you drive a few miles then shut it off that advances sludge issues. Make sure you get it fully warmed up. Toyota sent me the notice on the sludge issue in 1998. I have 327,000 miles on my Camry now. When I drive it I get it fully warmed up, and most days I put on at least 20 miles. I change oil every 4-5000 miles. These are great cars.
I never changed any of the common parts that fail on most American cars before 100,00 miles. Such as O2 sensors, alternator, starter, cv joints, all original still.

Vince Salmela