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Oil questions: How low should level get before top-off & Can you mix brands/viscosity

 
Old 01-15-2018, 09:45 AM
  #1  
K-A
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Default Oil questions: How low should level get before top-off & Can you mix brands/viscosity

The previous owner changed my cars oil about 11 months ago, while the car hasnít even been driven 2K miles since then (he literally changed the oil then parked the car, minus maybe occasional drives).

I checked the oil check meter while the car was off (hadnít been started for several hours) and it shows only two green bars (just the bottom two are green) while saying ďlevel ok.Ē

Questions are:

1: Is that (two green bars while car isnít on) low enough to need some topping off? If so, how much topping off?

2: He used Castrol Edge previously. Can I switch to Mobile 1 for the next change, or should I stay with Castrol?

3: Can I top off with Mobile 1 while there is Castrol Edge in there?

4: Can I mix viscosities for a top off (currently thereís Castrol 5/40 in there, and I happen to have a bottle of Mobile 1 0/40).

Iím not very oil literate past the basics of ďwhen to changeĒ etc. so any education is appreciated. Thanks.
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Old 01-15-2018, 09:54 AM
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You have to get it warmed up to temp, then you "force reset" the oil level by opening the engine cover then close it. Then get back in the car and check it. That's the procedure for checking level after an oil change anyway - which is supposed to be THE most accurate without a durametric or other device.

As to the amount - I would be very conservative like 1/2 qt tops. It's way more pain the *** to drain some out if it's overfilled. From everything I've read you don't want to overfill, being a little low but in the green is better.

As to mixing, I've always heard not to, but 1/2 a qt out of like 9 total may not matter for another month til you change it. Of course with a month out you might just leave it alone as long as it's in the green.
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Old 01-15-2018, 09:58 AM
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Gordon Shumway
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The proper way to check oil level is to have the car up to operating temperature, park on a flat surface, turn engine off, wait a minute, and then get a reading. Your two bars may or may not be accurate.
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Old 01-15-2018, 10:10 AM
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Originally Posted by Dude174 View Post
You have to get it warmed up to temp, then you "force reset" the oil level by opening the engine cover then close it. Then get back in the car and check it. That's the procedure for checking level after an oil change anyway - which is supposed to be THE most accurate without a durametric or other device.

As to the amount - I would be very conservative like 1/2 qt tops. It's way more pain the *** to drain some out if it's overfilled. From everything I've read you don't want to overfill, being a little low but in the green is better.

As to mixing, I've always heard not to, but 1/2 a qt out of like 9 total may not matter for another month til you change it. Of course with a month out you might just leave it alone as long as it's in the green.
Originally Posted by Gordon Shumway View Post
The proper way to check oil level is to have the car up to operating temperature, park on a flat surface, turn engine off, wait a minute, and then get a reading. Your two bars may or may not be accurate.
Thanks. Iíll check it the proper way next time I drive it. I had googled pics of 991 oil levels, and started to see cars with like 5 green bars, which is what got me curious as to my level.

For mixing. Would it be the mixing of brands, or viscosities thatís generally more frowned upon? Though like you mentioned, a top off shouldnít matter. But being that Iíd be mixing a different brand and viscosity, I just want be be sure before Iíd put a drop in it.
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Old 01-15-2018, 10:19 AM
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For reference, at least in the 991.1....I believe the difference between max and min is approx. 1.8 quarts.
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Old 01-15-2018, 11:23 AM
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As long as they meet the same spec - and specified for your engine - they are compatible. That is the purpose of specifications. However, this doesn't matter when things just "bug" you because there just not the exact same. Why not just pick up a quart of the exact same Castrol and use it until the next oil change? After that use remaining in your lawnmower or on a squeeky door hinge that you want to preserve for the next three centuries.
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Old 01-15-2018, 11:28 AM
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Gordon gave you great info. Follow it.

Each Bar is about 400 mls. Only add about 200 mls between drive cycles till you nail the level you want. Under is better than over.

Don't mix oil brands. Different brands have different additive packages that can fight each other.

Mixing same brands and different viscosities is OK, but always best to pick the viscosity you want and not try to play petroleum chemist. Topping up with different viscosities is a non issue (assuming same brand).
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Old 01-15-2018, 11:43 AM
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As to your 2nd question, you can change brands at your next change.
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Old 01-15-2018, 11:48 AM
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Originally Posted by Jaws1
As to your 2nd question, you can change brands at your next change.
Agree.
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Old 01-15-2018, 12:23 PM
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One point makes no sense and that is that mixing to top up is not ok but changing brands at the next interval is ok. There will be a lot of left over oil after a change. Personally I think mixing brands/viscosities is a non-issue. Maybe I am a bit of a codger, but I change my oil so much you can never see it on the dipstick with any oil so I sometimes throw a quart of royal purple in so I can see the oil on the stick.
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Old 01-15-2018, 12:47 PM
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My suggestion is to just change the oil. 11 months is close enough to a year and this way you know exactly what and exactly how much is used. When in doubt - an oil change is cheap insurance and it needs to be done annually regardless of miles anyway IMO - YMMV.
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Old 01-15-2018, 01:20 PM
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Mobil, not Mobile.

Sorry, I know it's a bit of a d!ck comment but I do have a reason to care.

Agreed with R rated, just change it now. Also, I would not be concerned with 2 bars down.
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Old 01-15-2018, 03:33 PM
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if you know what he used, use the same thing. When you start changing it, stick with the same oil all the time. personally if I knew what it had new, I would keep the same thing and never switch
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Old 01-15-2018, 03:42 PM
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2 bars is actually perfect. The biggest pain with oil in these engines is actually overfilling them. If you really do need a top up, the car will let you know and tell you how much is needed. If its anything like other cars I've owned the top up message pops up before you're really at levels that pose any sort of risk so you should have plenty of wiggle room.
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Old 01-15-2018, 03:43 PM
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Originally Posted by okbarnett
personally if I knew what it had new, I would keep the same thing and never switch
All new cars leave the factory with Mobil 0W40. You really didn't know that?
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