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Old 08-01-2018, 10:28 AM   #1
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Mixing motor oils

(Stupid but interesting background)

There is a lot of drama surrounding the LR4 oil requirements.

Bottom line: the car officially requires an unobtanium Castrol OE oil (it appears that in the past year Amsoil may have come up with one that straight-up complies). Most dealers don't sell it (some don't want to, others just get massive drum and can't sell it).

That leaves the unlucky few (like me) to resort to ebay to source it at $10+ a quart. Which, BTW, is cheaper per quart than what the few dealers that do sell it sell it for.

For fear of warranty denials, I stuck to that ridiculous requirement during the warranty period. When the warranty expired, I did a baseline Blackstone lab test on the used OE Castrol, and went with Mobil1 EP - a motor oil that by nearly all accounts complies with the spec.

Ultimately, that hard-to-meet spec seems to relate to long oil service intervals anyway. LR's interval is 15k miles, which as we know, is dumb. I happen to put at most 7.5k miles/year (nowadays more like 5k/year), so the yearly change is plenty frequent enough to effectively not have to worry about any of this nonsense provided a use a decent quality oil.


I have a leftover quart of the unobtanium Castrol OE oil. The last oil change, I filled with only Mobil1 EP.

For the next oil change, can I use up that quart and fill the rest with Mobil1 EP? They are the same 5W-20 weight.
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Old 08-01-2018, 12:49 PM   #2
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Quote:
Originally Posted by FC View Post
I have a leftover quart of the unobtanium Castrol OE oil. The last oil change, I filled with only Mobil1 EP.

For the next oil change, can I use up that quart and fill the rest with Mobil1 EP? They are the same 5W-20 weight.
Sell the unobtanium on ebay to pay for a full pan of Mobil 1 EP? If not, mix and match and don't worry.
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Old 08-01-2018, 01:26 PM   #3
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Sell the unobtanium on ebay to pay for a full pan of Mobil 1 EP? If not, mix and match and don't worry.
Thanks! I thought it would be ok. SUV takes 8 quarts (5.0L V8)

I've considered the ebay route, bu tit is probably more trouble than it is worth.
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Old 08-01-2018, 03:56 PM   #4
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Isn't oil mixed when adding a quart ? I know when my cars are low and I add a quart I go to the local gas station (usually Mobil) and get a quart that meets the requirements of the manufacturer. I have no idea what type & weight of oil the dealer is putting in my cars
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Old 08-01-2018, 08:13 PM   #5
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It’s basically fine. Although I don’t really think it’s worth it, given how absurdly cheap the Mobil is.
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Old 08-01-2018, 08:24 PM   #6
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Itís basically fine. Although I donít really think itís worth it, given how absurdly cheap the Mobil is.
I could care less about the Mobil. It's about the Castrol quart sitting there.
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Old 08-01-2018, 08:56 PM   #7
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15k intervals aren't necessarily stupid. It depends on how badly the engine shears the oil.

My truck requests an oil change every 15k mileage, roughly.

Anyway. Yeah. Mix without worry.
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Old 08-01-2018, 09:48 PM   #8
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Mix it in. What are you going to do, sell it for $6?
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Old 08-01-2018, 10:32 PM   #9
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Mix it in. What are you going to do, sell it for $6?
Exactly. I figured it was safe.
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