Switch to Mobil One 15w-50?

[trickyrix]

Right now I'm running Mobil One 10w-30 in my car, but I've got a bunch of 15w-50 sitting around the house. Since summer's right around the corner (and I've got the intermittent ticky lifters), I thought I'd switch to the heavier stuff. would I run into any problems using 15w-50? What do most of you guys run in your cars?

[cam76034]

Well you could try google and waste the rest of your weekend reading the pros and cons...and still be confabulated by the end of the day.

The oil performs as a 15w at cold startup, and a 50w when its hot. If it were me, I'd go ahead and run it this summer.

[Titus]

I tried dino, synthetic blend, and full synthetic in many different weights the first few years I had my Miata. I logged the point when HLA noise became constant (not just at start-up) and the length of time HLA noise remained at startup the day after the oil change, 1k miles after the change, and 2k miles after the change. I found that with Dino, the HLA noise was constant by 1k miles. The Synthetic Blend would get constant noise by 2k. Full synthetic never gets constant noise in the 3k miles before the next change. That was when I started messing with weights. I landed on Mobile 1 5W-30, as it thinner oil seemed to move into the lifters and quiet them down the quickest.

[trickyrix]

I tried dino, synthetic blend, and full synthetic in many different weights the first few years I had my Miata. I logged the point when HLA noise became constant (not just at start-up) and the length of time HLA noise remained at startup the day after the oil change, 1k miles after the change, and 2k miles after the change. I found that with Dino, the HLA noise was constant by 1k miles. The Synthetic Blend would get constant noise by 2k. Full synthetic never gets constant noise in the 3k miles before the next change. That was when I started messing with weights. I landed on Mobile 1 5W-30, as it thinner oil seemed to move into the lifters and quiet them down the quickest.

Interesting study! My lifters let me know when it's time to change the oil... At first, I get a little bit of rattle on startup, but it goes away almost instantly. As the oil ages, the the ticking becomes intermittent - often cropping up on a hot day of hard city driving. I've got just over 3K miles on the last oil change, and I'm ticking more frequently, and longer on startup.

[VFR750]

Titus is correct, the thinner oil will help the ticking, not the thicker stuff. Most people think its the other way around...............

[MadMerv]

No reason to use heavy oil in a Miata. It just slows the little 4-banger down. These cars have nice tight bearing clearences, so a thinner oil is better. I know a lot of racers run heavy wieght oil, only because this was "old school", but I guarentee you'll make more power with a straight 20W or 30W.

[Darron65]

Titus is correct, the thinner oil will help the ticking, not the thicker stuff. Most people think its the other way around...............

This implies the problem lies in the oil supply to the lifters, not the lifters themselves. Interesting stuff.
Modern thinking on oil selection is to use the lowest possible viscosity in the highest possible quality oil.

[icepenguin66]

You'll be fine, especially how hot it gets down here. Just make sure it warms up in the morning if a cold front comes in or something. That's what I ran in my Z28 when I had it.

[cam76034]

If you decide not to use it (the 15w50) I'll take it.

[smartmx5]

Use Marvel Mystery oil and clean out your motor, then use the 15w50. I, too, had Mobile 1 15w50 laying around, used it and it quieted down the HLAs tremendously. I now run Royal Purple in the bugger just because (as a post earlier alluded to about reading about oils all weekend), I plan to have my car on an SCCA or NASA track soon. Still runs quiet.

[MX-5EE]

No reason to use heavy oil in a Miata. It just slows the little 4-banger down. These cars have nice tight bearing clearences, so a thinner oil is better. I know a lot of racers run heavy wieght oil, only because this was "old school", but I guarentee you'll make more power with a straight 20W or 30W.

An exception would be to use a slightly thicker oil if the engine is leaking oil, like my Nissan KA24DE did. In that case I used one weight thicker, in the case of the KA24DE going from 5W-30 to 10W-40. Believe it or not this did help the engine retain oil (it was leaking through the front timing cover). It didn't stop the loss but it slowed it.

Note, I wouldn't go any higher than one step up. I suspect that 15W-50 might be too thick.

[Machismo]

Yep, thicker will slow it down. This is an old Chevy trick. Of course, if it ain't leaking, it doesn't have any. Less friction is the key, and thinner oil will do that for you. The only time I've run heavier weights was in the summer in Phoenix, AZ. Then just stepped up one weight-40W. As for the lifters, there are also oil boosters that should help quiet some of the noise for you.

[trickyrix]

Okay... I thought I'd share my update with y'all. After reading about the 2Twistys flush, and mulling over all the oil choices in front of me, here's what I did:

3Q of 5W-30
1Q of ATF
(both synthetic, leftover in the garage... yes, yes, I know I'm burnin' $$, but not really )

Anyhow... I got everything buttoned up and fired the motor. I got some "cold ticking" until the lifters pumped up, then I went for a short drive around the 'hood - nice 'n' easy, no redline runs. So far, it seems quieter than ever, but that could just be my imagination. I'm going to run this mix for a little bit and see what it does.

I'll keep you posted...

[cam76034]

How long are you supposed to run that through? Not too long, iirc.

[trickyrix]

How long are you supposed to run that through? Not too long, iirc.

If you use the 2Twisty method, you use 3 parts ATF and 1 part oil, and you run it in for an hour. Then you drain that and chase it out with kerosene.

I'm running the opposite mix and that ought to be good for a standard oil change of 3K miles (I get that from a friend who's been a mechanic for 40-odd years, and a Honda guy for 20). I'll keep my eyes and ears on it and won't run it too hard in the meantime. I'll probably change the oil again in 500-1K and run a kerosene chaser through before I add new stuff.

[Radio-Active]

That ought to test out them oil seals!

[SirHustlerEsq]

the 1qt of atf works, but frees up so much gunk that I wouldn't run it for more than 100 miles or so.

[trickyrix]

The ATF works.

...so you tried the ATF?

Did it shut the lifters up, or did it result in...



Thank you! And don't forget to tip your bartender!

[Radio-Active]

I lived just North of Waco back in 1991.

David

[cam76034]

I'll probably change the oil again in 500-1K and run a kerosene chaser through before I add new stuff.

Ummmm...kerosene chasers. Reminds me of my college days.