Is it just me or did I feel a slight loss of power when switching oil today from 5w-30 mobil 1 to 10w-40 mobil driveclean plus. Is this possible or is it just me. ps I also did a seafoam cleaning as well.

 

i have a lifter that taps so i switched from 5w 30 - 15w 50 so more oil would stay in the top of the motor and i noticed no loss in power at all.

did you change the plugs after the seafoam? may have some carbon deposits fouling out a plug or something.

-Grant

 

If you truly did feel a performance loss, my guess would be the extra effort your engine must make to turn the thicker viscosity of the heaver weight oil, and the fact that dino oil is not as "slippery" as synthetics. Thus a higher coefficient of friction. I really doubt you could feel a difference, as less than 10 horsepower difference really won't register on the "butt-o-meter".

 

its all in your head, changing to a thicker oil will not give you loss of power high enough to feel it as stated in the other post

 

You might have lost 1 or 2hp, but your engine will thank you for it since that 10w40 will protect better than 5w30 Mobil 1, which is almost a 5w20 and is too thin for the LT1.

 

Wrong on both accounts. 10w40 does not flow as well as 5w30, thus increased dry start wear, where 99.9% of all internal wear comes from.

5w30 is also the recommended oil from GM, who knows a thing or two about oiling. Also, I would much rather have synthetic 5w30 than dino 10w40. Synthetic can handle much higher temps and the film strength of the lighter synthetic will be higher than the next grade up of dino oil.

So I don't think his engine will be thanking him!

 

I can tell you this much. All the other stuff aside. Just make sure you change it on a regular basis (3k). I used 10-30 synthetic oil on my car and changed it every 5K because it was so called "synthetic". I know a lot of mechanics who will not use synthetic oil. From here on out I wont either. Everyone has their own opinion but I used synthetic oil and spun 4,6,7,8 bearing on my crank with only 79K on my motor.

This motor I spent some bucks on and I'm using dino oil and changing it every 3k.

I know people will disagree with me but if you spent that much on SYnthetic oil and still blew your motor at 79k I think you would feel the same.

 

Just because you ran synthetic, doesn't mean you stretch the change intervals.

Pulled my motor at 67K after 3K Mobil 1 changes, and I could have put the motor right back together. Cross hatching was perfect, and the bearings looked great. Could have practically ate off the parts!

 

that's why if you check my 1st couple of sentences I said "just make sure you change it on a regular basis (3K).

 

Call me Crazy, but I've used Valvoline 5w-30 since the car has been new. Changed oil about every 1000 miles or so. 160,000 care free miles so far. (except for the infamous opti)

 

Every 1000 miles?? Well thank you for inviting me to call you crazy cuz I think you are I mean certainly you're not hurting anything by changing it that often but I think you could get a lot more use out of it. I change my Mobil 1 syn every 5k kilometers (or every three months, which ever comes first.. usualy the three months goes by first) but anyways... I just think you could get more of your moneys worth out of it IMO

Trevor

 

Holy ****! You changed the oil 3,000 times in motor by only 67,000 miles. That's hard-core dedication!

 

He should go to a 10w40 synthetic, as this would be better than dino, that is true.

However you are wrong about startup wear being 99.9% of the wear in an engine, as it certainly isn't the case in the summertime. If this were the case then you'd see a drastic difference in oil analysis results between 5w30 and 10w30 of the same brand, and you don't. I've switched back and forth myself, and see virtually identical wear numbers when these viscosities are used in the summer. In colder weather, yes, you want to go with a 0w or 5w oil for sure.

When you drive a car like an LT1 very hard, you need a thicker oil, otherwise even when that oil is warmed up, you'll see a lot of wear. In fact the hotter your oil temps, the greater the need for a thicker oil. If you saw how thin Mobil 1 5w30 gets at 250 degrees or hotter, you would see why I'm saying it won't protect a hard driven car as well as a good 10w40 synthetic will. Keep in mind that the clearances in an LT1 are rather loose compared to the average engine out there, so how can GM still recommend 5w30 as being the best oil? They do it for fuel economy, not for engine longevity. I sent the list of LT1 clearances to someone I know who is not only an expert on oil (he has actually created oils for race teams) but has built engines as well. He agreed with me that an LT1 that is driven hard would be better off with an oil that is around 13-14cst at 100c, so that's an oil in the low end of the 40wt scale.

Ideally though, if you find a good synthetic 0w40 or 5w40, then that's even better than 10w40 for year round useage. Or a 5w30 or 0w30 that is on the verge of being a 0w40 or 5w40 (such as Amsoil, Redline or German Castrol)

Keep in mind though, in the very hot summertime though, a 10w40 will flow pretty much exactly as well on startup as a 5w30 will.

 

There is simply no need to do it every 3k when you use a good synthetic, if you do an oil analysis at 3k, then continue to run that same oil up until 6k, you'll see that the wear numbers are the same for the 3-6k portion of the run compared to the first 3k. So in other words you are still getting just as good protection from wear in the last half of the run as you are in the first half. Trust me on this one, I've seen enough oil analysis results like this which prove my point. I'm not saying to go 25,000 miles on one oil change, but I will say that someone doing 5000 or 6000 mile oil changes is going to get just as long of an engine life as a guy doing 3000 mile oil changes.

 

Synthetic oils routinely have greater film strengths than dino oils of the next higher viscosity grade. I do like your idea about a good 5w-40 synthetic though. Sounds like the best of both worlds.

As for wear, startup wear outpaces all other wear by a mile, regardless of season. I'm sure that the difference between 5w30 and 10w40 wear-wise in the summertime is probably not much, but it's still there none the less.

Also, you should change your oil at 3K regardless of which brand, due to contaminant buildup. Is the oil good to 6K? Probably. But isn't the whole idea of sythetic oil about maximum protection? I wouldn't play around with longer change intervals when 3K has alot of proven success.