My 2001 Ford Focus has been leaking oil at the rear main seal. I want to clean the engine plate with a degreaser (soapy water) and wipe it down.

Is it okay to spray it with soapy water, or should I leave it?

Photo of rear main seal

Motivation for this question

Nervous about accidentally harming the vehicle while acting on the intention of doing something good for it.

Follow-up question:

If it is okay, is there anything else I should do? (e.g. should I rub some kind of protective oil on it, or spray it down with brake cleaner, or do something else?)


I am going to replace the rear main seal.

Edit: The end result! enter image description here Not perfect, but much better!

  • I have always used brake cleaner and a small wire brush for this type of job.
    – Moab
    Commented Feb 12, 2019 at 0:04

1 Answer 1


Clean it. There's an old saying when working on engines: A clean engine is a happy engine. That goes outside as well as in. The grease and grime isn't good for the engine. By cleaning it up, it allows you to see new leaks as they happen. It's just better to have a clean engine.

Use soap/water if that's what you have. You can also use degreaser if you want to purchase it. You can also use typical household cleaners like Simply Green or the "Purple" cleaners will work as well. Just ensure you clean this stuff off well when done, as it can do a number on your aluminum parts if left on them for a long period of time.

  • The grease and grime isn't good for the engine. - despite quicker spotting new leaks, how being clean affects the engine performance or lifespan? IMO it doesn't really matter and by excessive cleaning (specifically with water) we can do more harm than good (electric connectors, wires, grounding points, electronic components are prone to faster corrosion if we accidentally spill some water on them while cleaning the engine block for example).
    – Mark
    Commented Feb 13, 2019 at 7:39
  • @Mark - A clean engine runs more efficiently. It's not just me who thinks so.. Plus the grime and crud which is on the engine will do a lot more damage to the electrical connectors, wires, and grounding points, than will accidentally spilling some water on them while cleaning the engine block. Think about how much water gets transferred to your engine compartment when it's raining while driving. Most cars are made to handle it. Don't consider this "excessive cleaning" but rather required cleaning. Commented Feb 13, 2019 at 13:21
  • I've never witnessed anyone who overheated his engine because of the grime and crud on the engine itself (and I'm talking about modern water cooled engines). But I've seen at least few cases where people had electrical problems shortly after or after some time caused by cleaning their engines with pressure washer, despite having junction boxes and other modules secured with plastic bags. There is a huge difference with rain going through the radiator or being splashed from the puddles, but the pressure required to clean the engine block easily forces it's way through the cable seals.
    – Mark
    Commented Feb 13, 2019 at 13:29
  • @Mark - Who said "overheated"? I said it runs more efficiently. Cleaning your engine is a good thing. For the reasons mentioned and because it just looks better, it is not a bad thing. Also, who said anything about "pressure"? I didn't say use a pressure washer. Use soap/water and elbow grease. It doesn't require pressure to make it happen. The OP is cleaning the back of the block where there aren't any connectors which can have issues. Bag the one open connector in the picture and have at it. Commented Feb 13, 2019 at 14:11
  • A clean engine also makes it more obvious when there is a problem like, for instance, leaking oil seals like the OP has been dealing with. There’s a reason that a lot of race teams will paint everything silver or light grey.
    – Bob Cross
    Commented Feb 13, 2019 at 17:45

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .