Oil change mystery?

[jsz]

I've been doing my own oil changes for the last 5 years on my 2002 21v w/ a merc 350. This year I noticed a few strange things.

I checked the oil level (almost to the "F") and then I warmed the motor up until it was hot. I then used the drain tube out the bildge hole. This time I decided to measure how much came out. The boat calls for 5 qts but after 4 hours of draining only 3 qts came out and that includes the oil from the old filter. I raised and lowered the bow to see if that would change anything and it did not. It also seemed to come out much slower this time. I even blew into the hose to see if anything was clogging it and it was clear.

I don't want to run it low on oil but after putting 4 qts back in, it is over the full mark. I wonder if that will drop a little after the motor is ran?

It seems like all the old oil did not come out but since the oil drain tube is connected to the bottom of the drain pan I thought it would get more that 3 qts.

How much oil are you guys emptying vs. the capacity?

[scoot18]

I learned the same lesson. 07 22Ve and this M/P5.7 only holds 4 qts. The first few times I changed the oil I was only getting 3.5 qts of oil out, I thought I had a serious consumption issue, but it turns out that it just holds 4 qts. I have never gotten a CONSISTENT answer from the ones who should know. But with my own checking I have found, 4 qts in and 4 qts out. I guess the oil pan is shallower for clearance reasons. ???????????????

[TeamAllen]

I've never measured the amount of oil coming out, so I don't know?

[Thomas Hohl]

Good question. Same thing happened to me. Well Tige gods, whats the real answer???

[jsz]

Thanks for the replies. Keep them comming.

[jsz]

New info just in...

I checked the oil again after changing it a month ago. It was still full. After starting it, it dropped to "low" so I added 1 more quart and brought it back to full. I thought it was wierd that the oil still looked "used" even though it was all new.

After about 10 minutes of running, I noticed the RPM's were still about 1400. They normally drop to 900 when it is warm. I let it go for a few more minutes and checked the oil again after the RPM's dropped. The level stayed the same but I noticed it was now perfectly clean.

I'm wondering if some sort of oil "gate" opens when the RPM's drop allowing "all" the oil to circulate???

I'm also wondering if I warmed the boat up enough the day I changed the oil. If it was not warmed up enough ("gate" closed), could this be the reason I only drained out 3 quarts???

[Oklahoma Breakdown]

I just changed my own oil for the first time this yeAR. After 4 hours of draining I prob only had just under 4 qts come out. I was worried I was doing something wrong so just left the drain tube open for a couple of days and it eventually all trickled out.
I will definitely warm the motor up next time first to loosen everything up.

[moved2ski]

I have learned to let the oil drain at least overnight, raise the bow with the jack, let is sit several hours, lower the bow for a few hours and you will get 4.5 qts + .5 in the filter. I over filld mine after not letting it fully drain.

[River Runner]

New info just in...

I checked the oil again after changing it a month ago. It was still full. After starting it, it dropped to "low" so I added 1 more quart and brought it back to full. I thought it was wierd that the oil still looked "used" even though it was all new.

After about 10 minutes of running, I noticed the RPM's were still about 1400. They normally drop to 900 when it is warm. I let it go for a few more minutes and checked the oil again after the RPM's dropped. The level stayed the same but I noticed it was now perfectly clean.

I'm wondering if some sort of oil "gate" opens when the RPM's drop allowing "all" the oil to circulate???

I'm also wondering if I warmed the boat up enough the day I changed the oil. If it was not warmed up enough ("gate" closed), could this be the reason I only drained out 3 quarts???

There is no oil "gate".

Your oil was full before starting because no oil was pumped into the filter. Depending on filter size, they can hold .5 to 1 quart.

Once the engine reaches operating temperature your RPM will return to base idle.

[jsz]

There is no oil "gate".

Your oil was full before starting because no oil was pumped into the filter. Depending on filter size, they can hold .5 to 1 quart.

Once the engine reaches operating temperature your RPM will return to base idle.

I pre-fill the filter before putting it on so that shouldn't change the level.

I guess oil "thermostat" would have been better than oil "gate". I have now heard from 2 people that say there is no such thing but it really acted like there was one.

[TeamAllen]

I have heard some arguments against pre-filling the filter, because that oil goes straight through the engine unfiltered. I'm not saying it's right or wrong, but some guys really get into this.

[jsz]

I'd like to know... It would be one less step for me

[chpthril]

I have heard some arguments against pre-filling the filter, because that oil goes straight through the engine unfiltered. I'm not saying it's right or wrong, but some guys really get into this.

I've be doing for years and highly recommend it. It's fresh new oil and it's only about .5 a qt.