Mixing Castrol syntec for a track day

[MikenOH]

A few weeks back, my mechanic replaced the M1 that was in the car--at my request --with Castrol syntec. I asked for 5W-40 but when he went tot he auto parts store all they had was 5W-30.

I have to say this has made the engine much quieter (2.7L Boxster) but after I checked out the Hot temp viscosity on this weight, I'm not sure its up to the demands of a 3 day DE.
(5W-40 is the recommended weight)

I'm thinking of draining 4 qts and adding 5W-50 syntec since I'd rather change out the whole crankcase of new oil to get a higher weight. I'm not real keen on this weight for a long period but I'm thinking it would fix the problem unit the next oil change in about a month.

Would appreciate any suggestions on this that you might have; thanks for any help in advance.

 

[IndyIan]

I have a bottle of syntec 5W40 with all the german car specs it meets listed on it. It has one on there for porsche, and I know neither the 5W30 or the 5W50 has those specs listed.
Probably you'd be fine with your plan, and for normal driving I think there would never be a problem, but depending how hard you thrash your motor on the track, switching it all to the right 5W40 maybe very cheap insurance. Especially if you are still in warranty.

 

[MikenOH]

Thanks for the reply.

I was hoping to avoid dumping the entire crankcase since the oil has less that 1K on it.

I hear what you're saying about the Porsche rating, but M1 0W-40 is on that list and I have to say after a couple track days, the engine did get noisy. I think the ACEA ratings mean more to me. The 5W-50 is not ACEA rated, so that prompts the question.

 

[ARCOgraphite]

I wouldnt be using 5w anything in a tracked car. M1 R 4T used to be one of the best formulated "track" oils you could buy in that weight (10w40) but IDK how the new formula performs. To Avoid dumping the whole sump, you could sub 1-2 qts with the 5w-50 but we dont know if the add packs are compatible.

 

[Astro14]

Sounds like you're going to worry about it on the track...If I were tracking the car, I wouldn't want to worry about it either...I would want to be certain that what is in the crankcase is recommended for the car, both in terms of viscosity and specification.

Replace it, you'll sleep better...

 

[chubbs1]

I am for mixing oils, (I get bashed for it too but you are taking that car out to the track, I would be on the safe side and change it out. Then change it again.

 

[IndyIan]

Originally Posted By: MikenOH
Thanks for the reply.

I was hoping to avoid dumping the entire crankcase since the oil has less that 1K on it.

I hear what you're saying about the Porsche rating, but M1 0W-40 is on that list and I have to say after a couple track days, the engine did get noisy. I think the ACEA ratings mean more to me. The 5W-50 is not ACEA rated, so that prompts the question.

You could keep your lightly used oil, run it in another car that isn't as sensitive to oil choice. I don't have any real data but the general consensus here is that regular syntec isn't that great and 5W50 will have lots of viscosity improvers that may quickly break down.
My personal solution for track use is rotella T 15W40, but I have no idea what my oil pressure is(I assume lower than new) or what my oil temps are(I assume high as I need to run the heater to keep the water temps reasonable). The only real negative to running thicker oil on the track is that if its not hot, it can build up in the valve cover with constant high rpms(maybe not as much as an issue with a flat engine?).
If you actually have oil pressure and temp data you can figure out what viscosity you need on the track.
Do some searching for posts by AEHass, he explains how to figure it out.
But if you just want to keep it simple, get an oil with the right specs and as small a viscosity range as possible, ie 10W40 is better for track use than 5W40 given everything else equal.

 

[2oldtommy]

IMO the important thing to look for would be an ACEA rating of A3. This provides an HT/HS of 3.5 or greater. I believe any oil on the Porsche list would have this requirement. FWIW==Oldtommy

 

[mechtech2]

I'd mix to get the viscosity you need for those high temps.

If you are really trying to save a buck, filter the old oil through some coffee filters and store it for use later in whatever vehicle!