I've read a few threads, and found some websites that suggest that you must use a flushing oil (0W20) before switching from mineral oil to synthetic. The mechanic I spoke with at the dealership said not so. I've got 26,800 mi. on my 2001 CL-S, and want to switch over to synth. Will I need to flush?

 

Total BS...

 

What he said..

 

You should just use whatever oil you are gonna lose to flush. I recommend flushing...just in case, if the oil that is used for flushing isn't dirty lookin as it comes out...you can stop. Usually, half a bottle is good enough.

 

Wait a moment... is flushing BS, or is flushing NOT BS. Sorry, I didn't quite catch that.

 

It's BS. Synthetic and mineral are compatible, so you don't need to flush it. If you let it drain out, there won't be much mineral oil left in the crankcase anyway.

 

I agree with Wires. No need to flush. Drain completly, change filter and fill with synthetic.

I use Mobil 1 5-30 synthetic and a K&N filter. Walmart Superstores carry the 5 quart containers for about $18.70.

 

Thanks, Guys.

 

Sells more oil to do a flush. Profit motive.

 

agree

 

But what about in a high mileage car, e.g. >100k miles? There was a post from a NASA engineer (I think) that suggested that it would be a good idea for high mileage cars switching from mineral to synthetics.

 

I think everybody here agrees that using synthetic oil is a plus.

 

I'm sorry. What I meant was, the post said that it would be good idea to flush in high mileage cars.

The "it" in the sentence refers to the flush.

 

Agreed. Whether you've got high or low mileage, you can benefit from synthetic, w/out a flush.

 

Just because he's a NASA engineer doesn't mean I'd let him work on my car.

The oils are compatible. If you want to waste a quart of oil go for it and flush it.

If you want to make it a little easier to get the old oil out then get the car nice and warmed up before changeing. Careful not to burn yourself but the old oil will all get out easier.

 

Thanks guys. I appreciate the info.