Don't mix oils! Oil pressure dropped ---
- Thread starter 70GS455
- Start date
Hmmmm.....you think installing 5.5 quarts in a sump where 5.2 are required would be hurtful? Or even 5 in a 5.2?
I think not typically.
Where did I say that it would be hurtful? I just prefer to fill it to the full line, that's all. My point was I use what ever other oil I have to get it there, since it requires a touch over 5 quarts. That bit of "mix" isn't an issue.
No, you took my comment wrong.
I though you were complaining about the odd ball left overs from an oil change. At that was the reason for mixing.
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When I originaly saw this post I didn't believe it.
This past week I went on a trip towing my t.t., shame on me not checking my oil level before I left.
I am running Quaker State High Mileage 5w30 well I get a low coolant on my dash, yep it's low, I decided to check my oil. It was at the bottom add mark, 1 qt low.
I run to publix to get distilled water and grab Valvoline MaxLife 5w30.
Go out the next day OMG my oil pressure at idle is at 20 psi 10-12 psi lower then normal . Thats a lot
This does not seem right, I have mixed other oil before many many times.
I may dump this mix this weekend
So I have 5 qts with about 1500 miles and 1 qt maxlife
This past week I went on a trip towing my t.t., shame on me not checking my oil level before I left.
I am running Quaker State High Mileage 5w30 well I get a low coolant on my dash, yep it's low, I decided to check my oil. It was at the bottom add mark, 1 qt low.
I run to publix to get distilled water and grab Valvoline MaxLife 5w30.
Go out the next day OMG my oil pressure at idle is at 20 psi 10-12 psi lower then normal . Thats a lot
This does not seem right, I have mixed other oil before many many times.
I may dump this mix this weekend
So I have 5 qts with about 1500 miles and 1 qt maxlife
It may have been missed that my conclusion was that it was not the mixing of oils but it was too much oil that was causing aeration and pressure drop. I will delete this thread soon
Ok thanks
There is a dry spec and wet spec for your engine. Usually 1 to 2 quarts stay in the engine on an oil change. So if you ever change brews your mixing oil.
Something else going on.
I think it was still a helpful discussion for future readers. Appreciate the follow up with the actual cause.
While I would not mix oils to come up with a unique blend I have used a different oil as make up oil, but almost always the same viscosity.
OVERKILL
$100 Site Donor 2021
I think it was an informative thread. The initial assumption was that it was aeration due to additive pack clash. It was instead aeration due to oil volume. Same diagnosis, different root cause, I think this is valuable.
CleanSump
Site Donor 2026
The outcome was interesting because one would normally use a windage tray to mitigate oil foaming. The fluid level turned out to be very important.
I am curious about the dyno part of the equation as a car typically rev this high would have flung oils in the engine all over thus lower the pickup, or have less oil to be near the crank, than a near stationary engine at dyno speed. I wonder how are the oil capacity calculated in design and whether they factor in how much would be needed and how much would start causing problem whether on dyno or on a track.
My late grandfather (passed away ca 1990) used to say keep the oil in the lower part of the safe range on the dip stick, not full all the way to the top, to get a little better gas mileage. He was an operating engineer (cranes and power shovels) with a lot of practical knowledge, and I think he had an intuitive feel for windage power loss.
Back when I was a kid , I was helping a neighbor change the oil in his old truck . Ford straight six engine . When I went to add the oil my neighbor told me that you always run a Ford a quart low .He said an old mechanic told him that . I've owned several Ford trucks and I just couldn't do it ....
Interesting ~ I have always Run 1/2 qt Low on all My Vehicles for 40 Plus Years
Even though My Honda will easily Rev to 6800 RPM - Generally always in 2000 ~ 5000 Rpm Range ..
Starting to see Special Built Pans through for Big HP & Big Turbo Guys that want to Spin 8000 Rpm's
Even though My Honda will easily Rev to 6800 RPM - Generally always in 2000 ~ 5000 Rpm Range ..
Starting to see Special Built Pans through for Big HP & Big Turbo Guys that want to Spin 8000 Rpm's
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