I have heard numerous people state that switching oil brands frequently (like whatever is on sale at the time you need an oil change) contributes to sludge formation. If the oils are quality oils, the vehicle doesn't have a problem, and the OCI's aren't excessively long, then how can this be?
someone explain switching & sludge
- Thread starter joel95ex
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Rumor, it's just that a Rumor. Oil compaines would like you to believe you should stick to one brand, their brand. Many respected members here have busted that myth though. I tend to stick to one brand [per vehicle], but lately with my beater I buy what ever is on sale.
It's not true. There are numerous members here who have switched oils based on what's on sale, combined oils of different brands, etc.
Be aware, though, that mixing oils may invalidate any warranty provided by the oil manufacturer (e.g. Mobil Clean 5000 is warranted against failure for 5,000 miles, but the warranty can be voided if you use other oils or additives) but otherwise should cause no harm.
Be aware, though, that mixing oils may invalidate any warranty provided by the oil manufacturer (e.g. Mobil Clean 5000 is warranted against failure for 5,000 miles, but the warranty can be voided if you use other oils or additives) but otherwise should cause no harm.
gathermewool
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The thing is, most oil companies use similar base stock, similar additives, and their oils perform similarly to their competitors, especially since most Americans think changing the oil at 5k is an extended drain...
Edit: By similar, I'm assuming we're comparing a group II/II+ to another of the same base stock, although mixing a group II/II+ with a group III would only give you a better overall base than what you had in to begin with. JMO
Edit: By similar, I'm assuming we're comparing a group II/II+ to another of the same base stock, although mixing a group II/II+ with a group III would only give you a better overall base than what you had in to begin with. JMO
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We'd see a lot of members with sludge around here if that was true.
I'm feeling cautious about running a different brand constantly. I've had some odd cleanups going on after OC with a supposedly clean engine. Case in point: the Castol syntec I ran after the valvoline synpower - the castrol seemed to "hate" whatever the synpower left behind. Oil kept getting mahogany brown and started using. Went to RT 10w-30 conventional and everything got back to "normal". Now thinking, it might be a best practice to find a fav brand and stick - plus you could then take advantage of the oil warranty (not that I've read any fine print to find their worth).
All of my cars would be sludged by now.
I constantly switch from Valvoline to chevron supreme and then maybee GTX or Mobil 5000 if the other 2 are sold out.
My Jeep has seen Valvoline, Chevron Supreme, Supertech, Mobil, GTX, and even a mix of all of the above.
It is true at least in my experience that if you stick with a certain oil then all of a sudden throw in a different one you will see some weird stuff happening.
For example our silverado used to see dealership oil changes for the first 45k miles then I did my own oil change with Valvoline white bottle (dealer uses PYB) and the Valvoline was very dark and thicker than normal. My guess is that it cleans whatever the pyb leaves behind due to different add packs. It even at up a little oil for the first 2 changes. All is normal now with the silverado on my 3rd change with it.
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eh, I can find no evidence that the myth is true. I have 3 conventional oils and 3 synthetic oils that I am constantly switching around. My GTP has almost 160K on it and have been opened up a couple of times (most recently 2008) for warranty recalls. I have taken a look at the inside of this SC 3.8 and it is very clean. We do have a 1986 Beater Mustang that I have owned forever, I just refuse to let it go. I have put all manner of dirt cheap-o oil into it and have a OIC of 5k on it. It has 194k miles on it and has never had any work performed. she is tired but runs well. I am going to post photos if I ever need to retire the engine. If there is a chance of sludge, it would be in this engine.
The only thing I have noticed when switching between oils is some extra consumption for the first OCI. I switch between M1 5w40 TDT, M1 15w50, Rotella 5w40 and Rotella 15w40 through out the year and even (gasp) mix them.
Sludge is from:
Bad PCV systems - poor ventilation of the crankcase
Excess heat
Oil left in too long
Mix or change as much as you like - it is not a factor.
Bad PCV systems - poor ventilation of the crankcase
Excess heat
Oil left in too long
Mix or change as much as you like - it is not a factor.
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