Residual oil

[Bullet]

How much residual oil are you comfortable with at an oil change?

I used a mityvac on my last oil change on my 2007 FJ Cruiser. It take 5.5 quarts. I refiled with a five quart jug and rain it about a minute or so. I had approx 3-4 ounces of residual oil by judging the level on the dipstick. I’ve changed the oil probably 20 times and equally on the Tacoma so I’m pretty good at knowing how much oil moves the level on the dipstick.

So, how much left over oil is acceptable? If it matters the oil was changed from Valvoline to Mobil One.

 

[wpod]

It doesn't matter.

 

[tyman]

Whatever's in the oil filter

 

[nascarnation]

Since 99.97% of oil changes (possibly more) are done via removing the drain plug in the pan, the data confirms that method is not causing issues. Having said that, if you always remove the pan to change the oil, you'll never have to worry about stripping the drain plug threads.

 

[RazorsEdge]

I let the oil drain out for at least 30-40 minutes.

After that's done, everything is cleaned up and new oil is used with a filter and job done.

 

[JustN89]

I have a Fumoto drain valve on my Elantra that, because I’m not patient enough to let it drain all day, leaves about 8 ounces behind at each oil change. This works out pretty well though, as the manual calls for 4.2 quarts with filter change. I dump 4 quarts in and it’s right at the top mark on the dipstick. I’ve never worried about that remaining 8 ounces.

 

[CR94]

... I used a mityvac on my last oil change on my 2007 FJ Cruiser. It take 5.5 quarts. ... I had approx 3-4 ounces of residual oil by judging the level on the dipstick. ...

It's possible that after using the Mityvac, you had 3-4 ounces more residual than you would've by removing the drain plug. However, it's unlikely that you didn't have significantly more residual oil overall.

Toyota's service manual for my car, for example, shows 4.4 quarts (or 4.2 L) normal oil capacity with filter change, but 5.0 quarts (4.7 L) "dry fill" capacity. That implies there's about 0.6 quarts of residual oil after draining by removing the plug. (Incidentally, they list capacity without filter change as 4.1 quarts, meaning skipping the filter change increases residual by about 50%.)

 

[fsdork]

52.7 millilitres.

 

[ATex7239]

How much residual oil are you comfortable with at an oil change?

So, how much left over oil is acceptable? If it matters the oil was changed from Valvoline to Mobil One.

Comfort level is irrelevant. It is what it is. It doesn’t.

 

[CleanSump]

Not enough to make any difference in the longevity of the engine.

 

[Chris142]

3-4 oz mixed into 160 oz isn't anything to worry about.

 

[ka9mnx]

Never really gave it much thought.

Here's an interesting idea. Use the Mighty Vac to remove old oil. When done remove the drain plug to see if more oil comes out. I'd like to see that test since I don't trust the Mighty Vac.

 

[Astro14]

Never really gave it much thought.

Here's an interesting idea. Use the Mighty Vac to remove old oil. When done remove the drain plug to see if more oil comes out. I'd like to see that test since I don't trust the Mighty Vac.

On many cars, the Mityvac gets more than the drain plug. On some car models, oil suction is the recommended method for removal.

Sadly, mine don't work that well with the fluid extractor, just can't get the line into the bottom of the sump in the irregular pans, which is a shame, because it would make life much easier.

 

[Bullet]

Since 99.97% of oil changes (possibly more) are done via removing the drain plug in the pan, the data confirms that method is not causing issues. Having said that, if you always remove the pan to change the oil, you'll never have to worry about stripping the drain plug threads.

Well the plug normally is removed. Due to health reasons I couldn’t. I guess you enjoyed throwing insults, so run along the adults are talking here.

 

[Bullet]

Thanks for the replies.

 

[Shannow]

Given that the used oil is "activated", in terms of many of the anti wear compounds have been broken/oxidised, and are thus in their surface active state, I think a bit of resdual is probably technically better.

When I change oil in my cars (not the lease), I leave the filter on (the used filter filters dustout of the new oil better) for both effects. ..one of my cars, I just pulled 2 (of 7) litres out every 6 months...filter annually.

 

[dubber09]

If you ever take valve cover off you'll see some oil is there that will only wash off when engine runs. There is old oil leftovers, just don't think of it.