Is it safe to put high mileage oil in the engine, if the engine has regular oil in it already? I noticed my oil is a bit low and my engine has regular oil (penzzoil). I only have the Penzzoil "High mileage" so was wondering if it's ok to add the high mileage oil with the regular oil?

 

of course.. what kind of motor you have? stock? then it doesnt matter.. if you read the label it should say something like compatible with conventional oil or something like that.. its better to have any kind of oil then no oil at all.. but if I were you check for any leaks first.. then I would change my oil and start off fresh but if you dont have time and really need oil then you can look into that as a temporary solution

 

You should never use Pennzoil. I herd that if not changed EVERY 3000 miles it will turn into mud and sludge so easily and mess the motor up.

 

I have a stock engine. I though as long as they are the same brand they would be ok. Any experts agree or disagree with me?

 

I am an expert and I say YES its compatible! but read my first post again. I dont like to repeat myself

 

you'll be okay as long as your not mixing conventional oil and synthetic oil.

 

yes you can mix it no problem. but next oil change run Castro GTX or something else.

 

you can actually do that with castro

 

ah, i run mobil1 full synthetic and love it... but i know with that its strongly strongly advised to not mix with conventional haha.

 

I wouldnt say "never" but I do hate the smell of Pennzoil

 

Yes, there should be no problem at all with switching to a high mileage conventional oil. Occasionally people will have problems switching to a synthetic because it may uncover leaks that a conventional oil wouldn't get through, but most high mileage oils are conventional. This isn't the oil's fault: the oil is only pointing out a problem that already existed in the engine.

I've heard that you're not supposed to mix conventional and synthetic, but I've done it before when I had to with no ill effects.

I have often wondered though, what about a high mileage oil makes it better for high mileage cars? I have a sneaking suspicion that it's snake oil - just a way to charge a couple bucks more, but I dont' know for sure. I ran regular old conventional Castrol GTX through my y8 for 187K (changed every 3K-4500), and it was clean as a whistle, didn't leak anything, and didn't burn anything. I can't imagine that I would have gotten better results with a high mileage oil.


I, too have heard from multiple mechanics, that Pennzoil is junk. I have nothing to back this up, but I've heard it enough, from enough different people, that I no longer use Pennzoil.

Have never heard anything bad about Castrol GTX, and I run in in my CRV, along with occasional Valvoline. Nothing but Syntec for the GSR though.

 

Mine burns about 1 qt per 1000 miles with occasional VTEC use. Prev. owner used a quickie oil change place that provided Valvoline so that doesn't speak well for that brand. I keep seeing good things about Castrol GTX here so that's what I'll use on the next oil change.

 

Definitely no prob just wouldn't do it on a built or even high performance engine as stated earlier