Oil Change Question

I just purchased a Used Bayliner with a 5.7 Liter Merc. I took it in for an oil change and service. I check the oil today while doing some cleaning. The oil looked like it still had a couple quarts of dirty oil in the motor. Is this comon on inboards? Is it not possible to suck all the oil out of the motor. I am used to a clean oil change on my old outboard, now retired. Whats the deal, this just does not seem right. Any information would be appreciated.

oil change

I work at a Bayliner dealer in Wa. The way it is changed is to suck the oil out through the dip stick tube. there are two methods to accomplish this. Some dip sticks have a hose fitting on the tube. those you thread the hose on the pump straight to the tube. The older style has no hose thread on the tube. On those types you have to push a tube down the dip stick tube to pump the oil. If the tube (dip stick) is noot close to the bottom of the oil pan, some oil will be left in the pan. If the tube is not pushed all the way into the dip stick to the bottom of the pan, some oil will be left in.
Was this your first oil change on this used 5.7? If so. it's possible that there was a lot of sluge built up in the engine and maybee where the dirty lookiing oil came from.
I know that this only partially answers your question, and raises more. If it is not too far to take it back ot the dealer, you could get their opinion and maybee another change of oil for an inadequate change.
good luck.

When professional services rendered, then there should be a pro job done on the oil change. They know this. There is a kit that can be installed at the oil pan drain plug which will allows to drain all oil thru a tube which will come out thru the bilge/stern drain externally. Unfortuanately pricey but well worth it. If there is a sledge build up, it can be flushed with diesel fuel. An old trick thats not costly at all. I use to have an older motor that a water jacket on the manifold deteriorated sending water into oil system. After changing manifold, drained all oil & water out, idled engine only with diesel to circulate and displace water. Noticed how it cleaned out sledge. This works well with IO motors as long as you don't leave in very long and don't run engine above idle not much more than a minute maybe 2min at the most.

You have to be careful though Roger, some of those engines are held together by that sludge! LOL!!

Thanks for all the information everyone. The family of the previous owner who passed away this summer said that he was very careful with the maintenance on the motor and outdriver.

I checked the oil before taking it in and it was not that bad. Darkening, but not thick or sludgy at all. Greyish but not dark.

I simply think that I will purchase the equipment and do my own oil and out drive maintanence in the future.

The same dealer did not clean the air intake filter either. $300.00 worth of service and I am questioning weather I am getting what I paid for. The dealer I used before moving to where I live now was great. They are to far to take my boat for service, so I guess it is learning time.


Thanks again!

If you are considering using a synthetic oil, Amsoil makes a great product that prepares an old motor to use synthetics. You fill the block with it, run it thru then flush and fill with oil of choice.

Kinda like the old diesel trick, but its a product that is specifically designed to break down and remove sludge, eliminate all the old petroleum oils and prep the motor. I had one of those old 5.7's and it is almost impossible to get thick cold oil out of that skinny dipstick tube. Better to install that fitting so you can drain thru the crankcase/oil pan and get a complete drain.

Good Luck!!!

oil drain in the pan

HoweAboutMontana said:

If you are considering using a synthetic oil, Amsoil makes a great product that prepares an old motor to use synthetics. You fill the block with it, run it thru then flush and fill with oil of choice.

Kinda like the old diesel trick, but its a product that is specifically designed to break down and remove sludge, eliminate all the old petroleum oils and prep the motor. I had one of those old 5.7's and it is almost impossible to get thick cold oil out of that skinny dipstick tube. Better to install that fitting so you can drain thru the crankcase/oil pan and get a complete drain.

Good Luck!!!

Click to expand...

If you are planning to put a drain hose in the pan, as stated it can be expensive. On some boats , the only way to get there is to pull the engine. If you don't already have a remote oil filter that would be the time to add one.

Likely I am going to get the Oil pan drian installed. I really appreciate everyones input. Probably a spring job.