consumption went down with M1 in 35y/o 350 Olds

[caprice_2nv]

So I've been trying to decide on one brand and type of oil to stick with permanently on this engine, and the last change was with a mix of M1 15w50 and M1 5w20, because I bought the 15w50 and then after some more research decided it was way heavier than I needed in this engine that usually uses 1/2 to 1qt of oil in 3k miles.

So I mixed 1L of 5w20 to water down the 15w50, giving me something like a 12w38 or something. Anyways I've gone almost 4k miles now and it has basically not moved on the dipstick, and I've been driving it fairly hard at times.

I don't know if this is a sign that I should stick with M1 in a 0w40 or if it's just coincidence that it didn't use any this time. The oil is getting very dark looking and I'm ready to change it. I had bought GC to use next change but last time I used it I think it used 1qt in 3k.

I'm stuck on using a 0w30 or 0w40 or similar since I use it late into the fall and it gets fairly cold in the mornings even before we get snow.

You guys vote for M1 0w40 or GC 0w30? I'm pretty well stuck on either of these or Amsoil 0w30 or Pennzoil Platinum 5w30. These are the ones i can easily get here and I want to pick one and stick with it from now on. The PP obviously is the most economical choice since it goes on sale regularly for 5.50/L in a 4.4L jug. I bought the GC last time for $6.99/L on sale, regular 9.99/L. GC isn't on sale as often though.

 

[HangerHarley]

Wow!

 

[sangyup81]

M1 0w40 gets my vote

 

[Gary Allan]

Where's Tig?? He needs to hear this

(j/k

)



Whatever you chose, I'd use it for two consecutive OCI's and then test it.

I'd naturally recommend SSO, but I'd also recommend you do a sensible length interval to get your money's worth out of it. If you're willing to throw that need out the window, then use it. I'm sure GC or M1 0w-40 will work well, as would XD-3 0w-30/40.

My reading skills might be glitchy today, but I didn't see a total mileage, nor a distinct proposed OCI length. Where are we at there?

 

[caprice_2nv]

The engine is of unknown mileage, it's never been rebuilt as far as I can see but was re gasketed at least once before I did it. I've put almost over 40k miles on it since I put it in. If I was to guess I'd say it's well over 200k miles. Slightly low oil pressure at idle but jumps right up with any RPM.

My interval will be up to 5k, but it's stored for the winter, so it could be changed right before storage, sit for 5 or 6 months then run for 5k in the spring.

I know this sounds conservative, but it's an old engine, with a carburetor and it gets run hard at times. I'm not interested in any conventionals and still not sure I understand why HDEO's are always recommended for older engines, since they are primarily designed for a diesel engine. I'd rather stick with a PCMO.

 

[hounddog]

Every vehicle I have swapped over to Amsoil has always cut oil usage by very noticeable amounts.Had a 305 Chevy that used a quart of Castrol 10w30 per 1000 miles.One quart of Syntec per 2000 miles and then one quart of Amsoil every 4000 miles.I was under the impression good synthetics always cut oil usage.

 

[caprice_2nv]

Actually forgot to mention the 2nd last fill was 5w40 Amsoil euro formula and I ran it for just over 3k and it was 1/4 of a qt low at that point which I thought was pretty good.

 

[FL_Rob]

Question.If it's stored for winter ,why not just keep what oil you have in it now, then change to the 0w40 or whatever you like for storage rather than change based on color? By the way Iv'e had afew of these GM engines and they're not picky at all on oil.

 

[Gary Allan]

Quote:
I'm not interested in any conventionals and still not sure I understand why HDEO's are always recommended for older engines, since they are primarily designed for a diesel engine. I'd rather stick with a PCMO.


They tend to be more durable and have great deposit control. Not too many years before that engine was made.. 10w-40 was recommended. HDEO's appear to have increased availability in the 30 grades and have also expanded from conventional to semi-synth.

In your case you have no need for any cold properties in oil selection. You appear to never operate it in any cold weather. I'd extend my recommendation to Amsoil ACD. Not because it's an HDEO, but it's a monograde that qualifies as 10w-30. Nothing to shear and low volatility.

 

[caprice_2nv]

I'll be putting another 10-12k miles on it before its stored for winter, I'm going to switch to whatever oil I decide on right now. I know a lot of people say not to worry about the color, but it bothers me. I have to have clean looking oil in it so it's getting changed.

 

[mrsilv04]

Would Mobil 1 10w-40 High Mileage be an option, since you're not going to drive it in the winter months?

I do realize that you're in Canada, and that a 10w-40 may not work.

 

[caprice_2nv]

I wouldn't be completely against 10w40 M1 HM but I haven't seen it anywhere around here, only the 10w30. Since I will drive the car late into the fall enough to get cold temps just before we get any snow that sticks I'd prefer to have something more like a 0w30 or 5w30, but preferably something on the thicker side of the 30w.