A friend wants to go to Mobil One from the usual stuff in a 90. I assume you just drain the old oil and pour in the new. It's nothing like going back and forth from DexCool, right? TIA...

No big deal. You can go back and forth, but there is something to consider. Synthetic is a smaller molecule, so, it will find leaks that conventional won't. Also, I've read that synthetic will clean deposits that will also lead to leaks.
I run Mobil 1 in my 87, no problems, no leaks.

Go to Mobil's web site to see what they have to say. Later! Frank

Why waste the money though Tobi John? All he has to do is drain sump, swap filter, and refil with whatever he likes, but why Mobil One? Why not something decent?

Any good quality oil will clean deposits, any oil that doesnt is leaving deposits.

Nothing special about Mobil One mate, only rice burner drivers use it here. If he wants to go to synthetic tell him to go with German Castrol.

Castrol GTX 20-50.....30 years of success for me

Yep there is nothing wrong with Castrol of any sort mate

Do you have any actual data to back up Castrol? Used oil analysis or anything? Anything to support your anti-Mobil 1 claims?

I read on here awhile ago where you claimed Royal Purple machined an engine as it ran. I assume, you meant that it caused metal to metal wear due to poor lubrication. If memory serves, you had attributed 3 engine failures or other incidents to this phenomenon. While it is interesting that Royal Purple was being used in all three engines, you can't blame the oil for those failures without any actual proof. You can guess and conjecture all you want, but in the end all you are doing is making an educated guess. If you're confident that Royal Purple destroyed those engines, fine, by all means tell us. You should also quantify your opinions as opinions though, not fact. If you have facts, spit them out. If you have opinions, spit those out too, but at least let us know which is which.

I read atleast one post a day made by you that represents what is clearly your own opinion as immutable fact; which it most decidedly is not. Bring the tech once in awhile instead of "only rice burners use it down here." If only rice burners down there use it, and you've discovered through used oil analysis that Mobil 1 doesn't protect as well because there is XX% more bearing material in the oil than 'Brand X' oil after XXXX miles, that's one thing. Just discounting an oil because you've seen a group of people using it that you don't like is lame, and bears no place on a technical board.

Used oil analysis can be done by a ton of places, usually for less than $15 per sample. Most Heavy equipment dealers can do it nearly on the spot. Here in the States, CAT, John Deere, Komatsu, and several heavy truck places (Freight Liner, Peterbilt, etc...) all provide oil analysis service for about $12 a sample.

www.bobistheoilguy.com is probably the best oil forum on the net, lots of actual information there as opposed to opinions.

Check it out, read their forums, do your own research, and make up your own mind.

Good point.

I use nothing but Mobil 1 and have never had a problem. My 92 has 166k miles on it and doesn't burn a drop...leak, well, that's another story. I use it in our 1993 Jeep Cherokee, too. I let both motors go a good 6000 miles or 6 months with it. My mother-in-law uses it in her Camry, mostly because she gets the oil changed every 6 months and because the I-4 in there is prone to sludging.

Leakage is a real concern on an older engine. Just be forwarned.

I have had good luck with Valvoline Synpower, too.

Back in the day, I have used Castrol 20-50 and it worked great, but on a modern engine, post 1990, I would shy against it. These motors are WAY too tight inside...

In short, I have never had an engine of any kind ever fail due to oil failure. And I have driven a shit load of miles. As for Royal Purple, I have never heard of it causing an engine failure. Doesn't mean it hasn't happened, just means I am not aware of it. I would question the situation before the oil... who built the engines? Was it purely a random act? Were they three totally different people? Were they prone to keeping the oil in for 20k miles at a time?

Fellow Guru mctravisty is a Dodge tech, one of the best. He runs into Dodges with the 2.7l V6 all the time with internal failure due to sludging... and in every case, the oil change history is crap. If the oil is changed on time, either 3k miles with conventional or 6k on synthentics (or so) no problems. But some of these cars go 25k on a single oil change!!!!

No, and i dont need to prove anything either in order to offer my advice.

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Oil brand almost takes on a Chevy vs. Ford kind of feel. I'm no mechanic, but I have owned a lot of cars. From what I know, and what I've read, Bogus is spot on.
Change your oil, on time, and it almost doesn't matter what you use. I use Mobil 1 because it has a good reputation and I want the extended time between changes. In my Bonneville, since I drive it year round, I use conventional.

But the OP's question was: Is it a problem to switch? Answer: No. In fact, Valvoline sells a blend, a mix of conventional and synthetic. Pick what you feel is a good brand and keep it changed, and drive on.

GM went to recommending synthetic oil with the LT1 in '92 due to the higher engine operating temperature. On previous years there is little to nothing to be gained by switching to synthetic. Dino oil would be fine for him, the really important part is scheduled changes, a quality oil, and good filter.

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...and 30 years of changing formulas, that care more about emissions than performance or longevity.

What do you consider success? No siezed engines?

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Ok, how about if my engine is running at 300F oil temps, with an oil cooler?

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The product has changed, even if the viscosity hasn't.

Oh, and yes, if the engine hasn't siezed, that's a positive indicator of a good oil.

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You need a bigger oil cooler.

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Fixed it for you.

Thanks for the feedback guys, I'll pass it on...

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I ran that oil in all my race bikes.

I never had an engine seizure during a season.

Also you need to look into the ash content (or lack thereof) in Castrol vz other makes. Castrol is a much cleaner burning oil than any other make

Preemptive....

if you think you aren't burning any oil....that may be a problem.

That sounds like reason enough for me Jhammons, im sticking with Castrol.

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Or a new engine.

There is nothing wrong with any of the major brands.

After a while, tho, it becomes purely marketing. Mobil 1 is no better or worse than Valvoline which is on par with Castrol with is about the same as _____.

If you follow common sense and care, most any brand will work.

What CAN cause problems is the wrong viscosity. Too thick in a modern motor and you will hurt something. Too thin an an old motor and you won't have enough pressure.

10-30 is the best bet for just about any stock engine from about 1980 on. The more modern engines are now requiring 0-30. Use it. Unless the motor has been rebuilt, stick with what the manufacturer recommends. And that includes compensating for local weather conditions.

The only thing for sure is that no matter the forum, no matter the car or motorcycle, no matter what the topic of motor oil is always a lively read!

^I'll second that......There is an epic thread over on the RX-7 forum about Motor Oil....I just didn't have the energy to look it up, much less cross link it here.

I know, what I learned.....and it solidified what I already thought......soooooo.....that is good enough for me.

I have a '90 that I switched from conventional to Mobil 1, and the engine did start to leak oil, from around the distributor. Also, the '90 may have an oil cooler on it (mine does) that will make the switch unnessary. I don't drive my car enough to worry about how many miles between oil changes, I just change it twice a year.

Randy