Oil Level Increases

[nadeem]

I have a problem with my 280 SL (Model 1970). Engine Oil Level increases with time and it becomes thin as petrol is going in the sump, mixing with oil.

[Peter h]

I would look at the injection pump.
It may discharge gasoline into the engine oil.
Second, the engine and piston rings could be worn.
Peter

[nadeem]

What is the remedy if the injection pump is discharging gasoline into the engine oil?

[Peter h]

You should first have a mechanic test whether you have gasoline in the oil. Then whether it comes from the engine or the injection pump.
Peter

[Nicolas Aristodemou]

It is also likely that you have leaking fuel injectors..... Or leaking cold start valve..... I would look into these possibilities first before touching the fuel injection pump.

[Peter h]

Interesting, but we should get the gasoline into the oil circuit through defective injection nozzles or cold start nozzles.
Peter

[Nicolas Aristodemou]

“Interesting, but we should get the gasoline into the oil circuit through defective injection nozzles or cold start nozzles.”

Yes leaking fuel into the cylinders finds it’s way down the piston rings and ends up in the oil sump....

[stickandrudderman]

Use the search function and find out how to check for a leaking cold start injector valve.
If that isn't leaking then it's the pump (or the one-way valve in the oil supply line if your car is fitted with that arrangement.
It's not just elevated oil level and thinned oil you have to worry about.
The fuel contaminated oil willl soften oil seals, particularly front ctrank seal, so you'll get oil leaks which can only be rectified by replacing the seal.
You'll also have "bore wash" where the poil that is relied on to form th seal between rings and bores no longer functions resulting in loss of compression, smoking at the exhaust, poor starting and poor performance.