Pictured: Oil dipstick (2004 prius with Pennoil 5w30)

I would not say that the stain on the dipstick is "normal" but as long as the engine is running OK and there are no unusual noises or warning lights on, why worry?

 

Thats pretty normal for a car that spent it's life on dino oil usually crappo dealer vat oil. Lots of crankcase vapor. You'd be horrified if you pulled the valve cover.

If you want to really see some crap look in the throttle body.

 

That stuff will wipe away if you use acetone to clean it. soak it for a minute and wipe with a strong paper towel. You have to repeat it a few times but it will wipe away.

 

Mine looks the same. I'm not worried about mine (2006 with 165k miles). I used to use regular 5w30 every 5k. I now use full syn every 10k.


iPhone ?

 

Yep, its varnish. It's also all over inside the engine. It's from running too long with too low oil.

 

I googled 'varnish' and found

What is the resin in this case ? And why would running the car on low oil lead to precipitation ?

 

Not sure if you are really asking or just being sarcastic here.

Have you tried googling "engine varnish" instead?

 

Here's a pic of varnish on cams and such under a valve cover.

There are volatile components in oil that evaporate in use. These volatiles condense on cooler surfaces, and the color is tan/brown. This can be mitigated by using an oil with a low-volatility value (NOACK), changing oil sooner rather than later, or using an oil known for its cleansing properties (and/or synthetic oil.)

I've used a product called Auto-RX that did a job on cleaning this off. It worked great on one vehicle but not so great on another. I believe the difference was the oil splash pattern under the valve cover was excellen on one vehicle and lame on the other.

 

No sarcasm intended. Apologies, I know it can be difficult to tell on the internet.

Mr. Incredible's picture of the valves is interesting, since it looks like some components are heavily coated and others lightly or even not at all even though the metal is the same.

 

In my experience, varnish forms on parts that are splashed by oil, but not constantly immersed. Examples would be a valve cover or that upper part of dipstick as in the OP picture. It makes sense considering that varnish is caused by oxidation of long oil chains and if a part is not immersed in oil, it's exposed to blow-by gases.

Now, if one runs low oil level, oil and many engine parts will be hotter, speeding the varnish formation. I had a dipstick varnish, just like the OP, in my corolla when it started to drink oil and level dropped to lowish at the end of OCI. I cleaned that and there was no dipstick varnish anymore when I kept oil level at the high mark.

This is why the advice given on the priuschat to keep oil purposely low or use radiator blocking (to boost MPG) is wrong. That results in too hot oil, internal varnish, and oil coking in piston rings resulting in oil consumption later on.

 

I have/had the same varnish coating on my dip stick and the engine only has 43K on it. All dealer serviced oil changes by the original owner. No doubt the bulk oil they used. I cleaned the dip stick off but realize the internals look the same. So high miles aren't necessarily driving this symptom. Use quality products to minimize this situation. I'll start blending in higher detergent oils as I start servicing this car myself.

 

Yep dealer vat oil. Varnish no extra charge. Just move up to Mobil 1 5-30 and that will stop all that.

 

Steel wool will take that off also. Just wipe with a rag after so you don't introduce any of the steel wool into the engine.

 

You've got all the secrets to making cars look new again I used acetone before but steel wool sounds much easier.

 

I am not a fan of using harsh chemicals if it's not absolutely necessary.

 

Buy new dipstick from the dealer. They are not that expensive.

 

I don't believe it is damaged. It just needs to be cleaned.

I am also not a fan of buy a new one and throw the old one in a landfill somewhere.

 

Ever heard of recycling?