How to change unknown oil

I bought a '94 E250 van, 4.9 L strait 6 and I’m pretty sure the oil hasn’t been changed in well over a year. What’s the best way to proceed with an oil change?

Should I flush? If so, with what?

Some say flushing loosens up too many clumps at one time and 2-3 regular oil changes @ 1,000 miles apart will do the job.

What do you guys think?

Forget the flush

Drive the van for 10 minutes to get the oil hot

Then proceed to do a normal oil and filter change

The flush does just . . . flush your wallet

BTW . . . did some shop try to sell you an oil flush?

A lot of people only change their oil once a year. In between they just top off. This isn’t good for the engine, but unless there is evidence indicating there is an oil sludge problem (check engine light on, etc) – I don’t think there is a need to do anything other than just a normal oil and filter change at this point.

How To Change Unknown Oil?



What they said, except for the Valvoline. If you’re concerned, just change it, drive for a few hundred miles, and change it again. Probably a good idea if you do that if you don’t know about the service history.

Don’t flush, regardless.

Sorry @poopyhead_Mcgee but I have a fondness for Castrol, not valvoline

Flagged you as troll for “I have a fondness for your mom.” good day.

And for abuse.

Too bad no ‘clueless’ option…

Valvoline, Castrol, or even Wal Mart oil; if it’s the proper spec then it’s all good.

Unfortunately, the same can’t be said about your comments Poopyhead.

The original question and most of the responses are legitimate. Maybe the moderator will choose to remove the offending comment and even mine.


Back to the original post, sorry to flood your inbox, I think regular 3k mile oil change will work out fine.

Geez, use whatever oil you want… It’s not 1950–pretty much all oils are very good these days. I’m rather particular to Amsoil these days personally…

To answer the OP’s question: If you’re worried the oil is over dirty, buy some cheap oil, change it, then do another change very early, like at 1,000 miles with some better oil.

Change it now, use whatever decent oil you want, and don’t worry about it.

Just make sure the oil meets the specs specified in your owner’s manuals. 99% of the oils available (wherever you decide to buy it - including places like WalMart) will meet those specs.

Valvoline, Castrol, or even Wal Mart oil; if it's the proper spec then it's all good.

EXACTLY…It’s amazing how one person can possibly say that one oil is better then another. If ONE oil stood out as being so much superior…then we’d regularly see engines going over 1 million miles.

First, warm the motor and drain the old unknown oil. Replace the filter. Fill with a low cost oil, of the correct weight. Run that oil for about 1000 miles. Then change the oil and filter again and this time use any oil of your choice. Then change every 6 months or 5000K miles (whichever comes first) from then on.

Don’t overthink this. Oil changes are not a big deal. Just change it and move on to something that is actually deserving of your time and attention. Uncle Turbo and everyone else basically say just change the oil. You don’t say you have any symptoms of issues, so why make up an issue.

Just change the oil with whatever you want. Do the next oil change at 1K or 5K. It doesn’t matter.

Most of these posts are assuming , and you didn’t say, that there’s a problem with the van because of the unknown oil change time and mileage.
But if there’s no problem showing now…you can’t tell the condition of the oil untill you begin the oil change. At that time you can see the old oil and figure if it’s been too long or if this is just a routine oil change.
Those old 4.9 strait sixes were a good workhose engine and I doubt it will even know.

If OLM sez u can go 7k miles and u drive less than 7k miles per yr, what’s wrong with changing oil once per yr? Manual sez OLM or 1 yr interval. U add 1-2 qts per yr. that’s bad?