Higher oil consumption with synthetic oil

[OilUzer]

Originally Posted by CR94
Originally Posted by JAG
I still have not figured it out. Sometimes changing chemistry and increasing viscosity (HTHS viscosity) can cause drastically increased oil consumption. ...
Well, there's the hypothesis that high viscosity oil combined with low-tension rings can lead to excessively thick oil film remaining on cylinder walls when the piston descends. (I've read that, but don't know how often it actually occurs, if ever.)


Something about the rings "skipping" over the thicker oil. It was an interesting subject and totally opposite of what I would have guessed! don't remember the details.
iirc Shannow was the one posting about the "skip" concept. Not sure if he was explaining it or said he had read about it or what!

 

[kr_bitog]

Can it be just the coventional burns dirtier and create seal that reduce the consumption?

 

[FCD]

Originally Posted by kr_bitog
Can it be just the coventional burns dirtier and create seal that reduce the consumption?

Not really.
Oil of any base stock will leave deposits when burnt.

 

[Srt20]

I've used the Chevy crate engines in race cars before. Thats an awfully old 604. Im sure its just wore out. I usually changed the oil once a year. They would always use some oil, but 1 qt per 100 laps is kinda excessive. Those pans hold 7 qts, but I always ran 6 qts. M1 15w-50 is what GM specs for the engine.

The valve springs would need to be replaced alot more often then the oil needed to be changed.

 

[wtd]

That was my experience in the early 2000's on my 98 chevy truck with the 5.7L and my ex-wife's 98 Pontiac Grand Prix GT with the 3800 V6. Both vehicles consumed more oil when I switched them over to Mobil 1. I later went back to a conventional oil in both and the oil consumption went down quite a bit. One of the few reasons I don't like Mobil 1

 

[caprice_2nv]

Originally Posted by PimTac
Those old Monte Carlos would blow oil like no tomorrow. If he ran it on conventional for a long time then switched to Synthetic, the chances of oil loss and consumption go up. It happens a lot especially with old cars like that.


Since it's a crate 350 it's not the original engine to the car. Anyways my 305 in my 83 Caprice (same engine as that Monte Carlo could originally have had) doesn't use more oil with synthetic. It uses about a qt every 2500 miles with synthetic but most of that is because every gasket is leaking after 230k miles and 35 years. What do you expect? I've owned several of these and they don't usually blow oil like no tomorrow. If they do it's probably lack or maintenance.

 

[OilUzer]

Originally Posted by wtd
That was my experience in the early 2000's on my 98 chevy truck with the 5.7L and my ex-wife's 98 Pontiac Grand Prix GT with the 3800 V6. Both vehicles consumed more oil when I switched them over to Mobil 1. I later went back to a conventional oil in both and the oil consumption went down quite a bit. One of the few reasons I don't like Mobil 1



My 97 Tacoma burns very little oil with dino but when I was very busy i used to take it to dealer and they used syn-blend and it lost almost a quart very quickly. It happened couple of times with syn-blend. I asked dealer not to use syn-blend the second time and they still used it. The sticker showed syn-blend. That's when I found out they put 5Wx30 syn-blend in everything ... I switched to conventional (dino) of same grade and oil consumption went way down!
I asked one of the mechanics there and he said the synthetic is very slick

and he doesn't use it on his old cars either.
I am not sure about the "slick" theory

however there must some thing going on when using syn... since all oil websites (mobil, etc) tell you synthetic works in all cars even old cars but people have different experiences. Maybe oil companies want to sell the more expensive stuff and their web sites are not %100 truthful!

 

[PimTac]

The issue in general is running a engine in conventional for a long time then switching to a synthetic or blend. It won't happen every time but in general most engines will start consuming oil.

Sometimes it happens when switching brands after a long time using one brand.

 

[OilUzer]

Originally Posted by PimTac
The issue in general is running a engine in conventional for a long time then switching to a synthetic or blend. It won't happen every time but in general most engines will start consuming oil.

Sometimes it happens when switching brands after a long time using one brand.


I better stock up on Costco Chevron Supreme then

I use it for couple of older cars!
Is Costco CS same a real CS or is the watered down version? j/k

 

[dogememe]

Originally Posted by OilUzer
Originally Posted by PimTac
The issue in general is running a engine in conventional for a long time then switching to a synthetic or blend. It won't happen every time but in general most engines will start consuming oil.

Sometimes it happens when switching brands after a long time using one brand.


I better stock up on Costco Chevron Supreme then

I use it for couple of older cars!
Is Costco CS same a real CS or is the watered down version? j/k

Chevron Supreme is a syn blend in 5w-20 and 5w-30 flavors

 

[OilUzer]

You are correct!
CS 5Wx30 is syn-blend according to their website but it doesn't say anything about 10Wx30.
I now mostly use 10Wx30 and sometimes x40 in my Tacoma and 5Wx30 in another older car.