Varnish or surface rust?

[SomeName]

Single owner 2002 Grand AM. 93K on the clock, running Mobil 1 5W30 since it's first oil change at 2K when it developed a leaky rear seal. Or it's second change at 5K. We're not sure if the dealer actually poured in the M1, we heard afterwards from an employee that the grease monkeys at that dealership would keep premium oils for themselves, and pour in the bulk conventional oil. Never went back to that dealer.

Every change from 5K on was done by myself at whatever interval the oil life system said to change at with M1 and whatever filter we could get... mostly frams (yeah yeah, I know better now) So 4K-9K depending on the season. It was mostly driven easy highway 100 mile round trip commute. It seemed to do lower miles in winter, and late summer... but I digress....

At around 60K miles, it started to get lifter noise. tick tick tick..... until it would warm up. Different dealer said it was piston slap, but I didn’t believe it. Since I had no intention of fixing it, I decided to ignore it either way, as this car is paid for, and is a keeper, and nothing’s getting fixed until it breaks. Tick got worse as time went on.

The oil fill is large enough that I can see several rockers under the valve cover, and I always look in there when I fill with oil. At around 80K miles or so, I started to notice deposits on the roller rockers. Looks like rust, but could be varnish. It sort of rubs off if I reach in with my finger. How do I tell if it's light surface rust or varnish? It's on the roller rockers, and seems to be spotty on anything steel, but not on the aluminum heads. Nor the steel springs. Seemed to get worse up to 89K. At 89K, changed over to AMSOIL 5W30 Series 3000 Heavy Duty Diesel oil. 3K miles later, the deposits don’t appear any different, but that’s probably not long enough to notice a change. However, the tick has vanished at some point during the last 3K miles. I’m guessing that there may have been a gunked up lifter and the diesel oil cleaned it up.

So how do I tell if it’s rust or varnish?

 

[michaelc80]

I would run a course of AutoRX through it. The most likely candidate is varnish-if it is the AutoRX should clean it up.

It's hard for me to believe that oil coated engine internals could develop rust on a vehicle that's driven regularly but anything is possible.

It's also hard to believe that M1 would develop any significant varnish-but again...anything is possible.

You might check the PVC system to make sure it's up to snuff as well; it can cause sludge if it's not working correctly so it may be a contributing factor.

BTW-what part of Eastern Iowa are you in?

 

[SomeName]

From MXO. Smack dab between CID and DBQ. What part of central Iowa are you in? Two network guys with an interest in oil, in the same state, what are the odds?

It's not so much the burning desire to clean it out (it's not *huring* anything) but the desire to know what it is. If I can get some on to a Q-Tip, or scrape some off, how do I tell what it is? I can get a very little bit of it on my finger, but still... All I know is that there's an extremely small amount and that It's rusy colored. Are there any simple tests to determine rust from varnish when dealing with a very small amount of sample materail? If it's surface rust, will small amounts flake off/wash off and show up as elevated iron in the used oil analisis?

I want to isolate the problem before I think about a solution. Dumping in AutoRX is just throwing possible solutions at unknown problems. An oil sample should tell me if the PVC has failed. I check the PVC each time check/change air filter... guess I'm old school maintainance that way. I'll have an oil sample in a few weeks. The "fixed tick" has me wondering about what's going on under those valve covers.