hello,

i realize this is a thread that best belongs in non-year related forum, but i saw some folks viewing this forum and hoped someone could answer quickly. i'm in the middle of a project and could use some info right away. i've turned up little to nothing on a search.

quickly...
i rebuilt the top end of my '92 4rnr and this evening completed. went to add the oil back in, realized i overfilled, drained to start over, and discovered bubbles in the oil....plus a slight greenish tint. i noticed when i drained the oil it came out very dark at first, meaning i hadn't drained the oil when i started the rebuild. could have swarn i did. that was over a month ago when i started the project. anyway, the oil i added tonight was synthetic Mobil one. should be compatible with regular dino, right? it is cold, the original oil is dark and aged and has been sitting. could these be the possible causes for the bubbles...the mixing and the age?
and what of the tint? i figure the oil just has to be rather broken down because no headgaskets leaked and no coolant got in the block during the tear down. if any did, it was very, very little...but, i'm pretty certain that couldn't have happened. anyhow, can anyone offer some suggestions on the oil. i just want to use it to crank the motor and test it for success or failure on the rebuild....see if it runs.
hope this isn't a stupid question.

thanks

 

I know oil trickling into the already drained oil after the flow has slowed will often times cause bubbles. Usually if oil and antifreeze get together they don't mix well unless it's been started, and if that was the case the oil would be white\milky looking. I don't THINK synthetic and dino mix too well, but if you had all the oil drained when you added the synthetic it shouldn't have mattered. I don't know the details of your rebuild and how far you took the engine down, but keep in mind that when you drain the oil, most of the time some gets trapped in nooks and crannies in the engine, and some of the old oil won't come out. That *could* explain the black oil. Also, something else to think about when you get ready to add the break in oil is that alot of people break in an engine with dino oil. I can't remember exactly why, but you change break in oil before a regular oil change anyway, so you won't see too much of the benefits of synthetic that soon anyway. Breakin oil = lube the engine and catch little particles of metal from break in process. After that, I would switch to Mobile 1 because it's some REALLY good stuff. It's what I use in my street\strip mustang and my lifted V10 F250 Superduty. I use full synthetic in the stang and synthetic blend in the SD. May switch to full syn in it next oil change too. I just wanted to transition it over to it. Full synthetic oil WILL find any leaks you have too, so watch out.. LOL

PS. Where in AR are you from? I live in a small town north of Jonesboro in NE AR.