First time using synthetic oil usage increase

[2James1]

I got the car in my sig a few months ago. It has 155k on it now. Previous owner used Castrol GTX and Fram OCOD. He said it used 1 quart every 6k. Well I am using Mobil 1 5w30 and since the beginning of the last oci(5100 miles ago) I have added about 1.5 quarts is that an excessive increase for the first oil change of synthetic? I understand many times the first oci of a new oil especially synthetic oil usage may increase initially...but that much?

 

[Garak]

I wouldn't worry yet. Give it an OCI or two to get a real idea.

 

[Falken]

On my third fill, 1st FF, second was Mobil Super 1000 conventional, then the third fill was Pennzoil Ultra 5W20 SM, I had about 500ml of oil consumption.

I have only used Sopus syns since and now I get no noticeable oil usage.

 

[71Chevyguy]

Since you know the vehicle has a history of usage maybe you should consider a high mileage oil? Another thing I would do if it was mine is to check and/or replace the PCV valve if it is not too difficult to get to. Don't remember where they were on those. I know the older ones were a pain but I think those may be more accessible. Brand may also make a difference, you may want to switch it up and see if any other brand does better. This will be one of those play around with it till you get it right. FWIW I had a Bonneville that used oil and when I switched to Rotella T6 it never used a drop again for the next 60k I had it. Not recommending such a heavy oil but if you get no results from anything else then you can give that one a try. I would try the high mileage oil next oil change.

 

[Clevy]

It happens. As Garak said give it a few intervals.
What happens is the old oil has left an anti-wear layer on all the moving parts and cylinder bores. Now you've switched oils so the new oil is stripping the old oils anti-wear layer off,in doing that the cylinder bores have gotten bigger and the rings are no longer tight against the walls. Once the new oil lays down its new anti-wear layers on the bores will get that tiny bit smaller and consumption will cease.
New threads are posted every few days by new members concerned because before using M1 there was little to no consumption. I can't remember the last time we had a thread about consumption that wasn't in reference to Mobil 1.
Anyways just keep a close eye on it. I don't top up unless it needs a full quart then I don't have to drive around with an opened half bottle of oil which I'm sure will leak at some point.
Its good oil however if after your second interval the consumption hasn't stopped I'd be looking for a different oil.

 

[widman]

I second looking at the PCV.

And also that the new oil may be cleaning up things, which sometimes increases consumption.

I'd either try a high mileage or AutoRx to help with the cleanup.

 

[2James1]

Thank you for the replies so far everyone... please keep them coming. I will continue to monitor and top off(usually 8oz at a time... a little ocd maybe). If it doesn't improve in an oci or two may give Mobil 1 high mileage a try. Also anyone know where the PCV valve is on this car? If it's something I'm capable of replacing would be worth a try for $3.

 

[tig1]

I think the highest oil use of any engine I have owned in the last 35 years(I have used Mobil 1 oils since 1978 at 10K OCIs) was a qt every 3500 miles in my old Ranger 3.0. From day one until it had 354K the oil consumption stayed the same. Other engines used a qt every 6500, but my presant engines use no noticeable oil in 10K with 0-20.

 

[FZ1]

Switch to Mobil Super Hi Mileage 5w30 Blend. You don't want a synthetic in a leaker.

 

[JethroBodine]

Originally Posted By: FZ1
Switch to Mobil Super Hi Mileage 5w30 Blend. You don't want a synthetic in a leaker.


+1 or maxlife.

 

[TMoto]

Originally Posted By: widman
And also that the new oil may be cleaning up things, which sometimes increases consumption.

I'm curious as to why cleaning would increase usage? Unless it's cleaning the antiwear properties off as one of the earlier posts stated. I would think whatever is being cleaned would end up in the crankcase and show up as the sump level increasing slightly if at all.