While the drama is little high on this thread, it brings up an interesting topic of the dry and wet oil capacities. I really didn't think about it until now but there are a lot of hiding places for that oil. Besides the wet surfaces, the lifters, oil galleys (which can vary from tiny to open chambers), oil coolers, oil pumps and pick-up tubes. The tubes on an LS engine are good size and long! Could be the better part of a quart there.
Topping up a fill with a different brand
- Thread starter dwasifar
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Not sure who you're talking to. Just about everyone here agrees it doesn't matter.
I'm talking to the people that are arguing over how much oil is left in the engine .
Carlostrece
$100 Site Donor 2025
I prefer not to mix oils because their additive packages might not be fully compatible.
However, adding any brand of oil is better than being low on oil. So if it's a choice between adding a different oil (mixing oils) or being low on oil, then I'll add whatever brand is available whether it's same or slightly different viscosity.
However, adding any brand of oil is better than being low on oil. So if it's a choice between adding a different oil (mixing oils) or being low on oil, then I'll add whatever brand is available whether it's same or slightly different viscosity.
Patman
Staff member
I have always felt that if you are going to be doing extended intervals (let’s say 7k or more) that you ideally should not have vastly different brands of oils in there that might possibly be working against each other in areas such as TBN retention or oxidation for those longer runs.
In the case of my Civic, where I usually follow the OLM (which puts me at 10k OCIs) I don’t want to immediately go that long when switching brands. So when I’m done with this final interval with VRP and I switch over to ESP, my first interval with it will probably be around 6-7k and then I will go back to the full 10k on the second interval and beyond.
In the case of my Civic, where I usually follow the OLM (which puts me at 10k OCIs) I don’t want to immediately go that long when switching brands. So when I’m done with this final interval with VRP and I switch over to ESP, my first interval with it will probably be around 6-7k and then I will go back to the full 10k on the second interval and beyond.
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I totally agree, we tend to overthink things here. I would say if my crankcase is 5.5 qts, and for some odd reason I need to add 1 quart, it has 5W30 synth and I decide to put in 10W30 dino juice, well, I think the engine will be ok, but I would now consider the properties of the lower oil not the higher. But if I put 5W30 of another brand synth, I wouldn't even think twice.As other have said, its not a big deal. I like to try to stick to the same brand if I mix, but not really a huge issue. Unless you are using something totally different like M1 0W-40 with a top off of canola oil. That's where I draw the line.
I know that nobody here would do this, but I just changed my oil on the "9 HP" Tecumseh snow blower, before storing it for the season. It's only the 2nd time I did it, in its life. The last time was around 2006. Believe me, the machine is fine and it will be fine next winter. Yes I should have changed the oil more, but can you imagine another person may have changed it every year? What difference would it have made?
Last thought, there is a tendency to draw conclusions without any real world data. And that is perfectly fine when one has significant resources, which is this forum!
As I said , I have done it MANY times with NO negative results while others here speculate on what MIGHT happen . I'm always going to stick with real world experience over speculation . However , people need to do what makes them feel comfortable so mix or don't mix as you see fit .
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True, but at the same time, haven't a lot of the additives been reduced by that point? So combined with the general reduction of additives, with the reduction in mass, there doesn't seem to be much to cause chemistry interference.
Well, I'm a bit different in this conversation. I cannot add oil into my two car engines because neither is an oil burner. My 2020 Chevrolet Equinox 2.0L GDI and my 2008 Honda Civic appear strait up to capacity when oil change time comes around. I'm 86 years old and I still do the maintenance on these cars. I started fixing my cars when I was 17. I did this on my cars and for others who were unable to do their own. If I were to need to top off it would be the same as is already in them. That just hasn't happened to me yet.
I think we need to educated so we don't feel uncomfortable. CCS and MRV is another issue, but the engine talks and should tell you it doesn't like something. You just need to acquire Horsepower Whisperer skills
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My relatives aren't diligent about changing oil in outdoor power equipment other than their chain saws, and it's been at least forty years since I've seen any of it require replacement due to a worn-out engine.
Rust, metal fatigue, accidental damage, and spare parts unavailability for the rest of the machine is what kills 'em. Your showblower's engine will probably still be OK when you retire the unit due to some other component failure that can no longer be repaired.
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For top offs specifically it isn’t a huge deal either way IMO. The amounts aren’t much different than from brand swapping from change to change.
Carlostrece
$100 Site Donor 2025
Lake Speed Jr tested this topic using UOAs of 2 different oils, and a mix of those 2 oils. His UOAs proved that mixings brands sometimes results in reduced oil performance.
However, a little extra wear won't be noticed by a car owner if they're not carefully tracking wear using UOAs.
A little bit of extra wear won't reduce engine lifespan enough to notice or care if you occasionally mix oils, but if it's a regular ongoing habit it adds up over time.
I don't hesitate to add a quart of another brand if I'm low on oil and my normal brand isn't conveniently available, but when it's conveniently available I add the same brand that's already in the engine.
Can you mix brands? Yes.
Should you mix brands? It depends on circumstances. I'd rather mix than be low.
OVERKILL
$100 Site Donor 2021
You need an obscene amount of data to even begin to gain useful "wear" data from UOA's, and really, would still have to verify it with tear-downs because UOA's only measure particles under 5 microns and the magnitude bands over the wear range are not discernable from a UOA.
Definitely, but I would also question how different the additive packages are that there is actually some observable reaction. My thought is that if you had PYB in the crankcase, and switched over to Quaker State Full Syn, that absolutely nothing…NOTHING to do with oil interaction would occur.
This might have been a question asted50 years ago and the answer is the same
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