Got my car serviced (2015 Vantage V8S) and noticed the dealer switched from Castrol to Liqui Molly 10w60.

Is this cool? I've now got 3 bottles of castrol. Can I "top off" using the castrol. Does anyone know of any reason why I wouldn't want to mix oils, or should I drain the Liqui Molly and stick to Castrol?

 

I get the trepidation when dealing with an expensive car that you love, but if it's one quality brand vs another there isn't much to worry about if you're using the same weight. Maybe if you were to use enough of a lighter weight to dilute the 10W-60.

 

There's no issue under normal driving conditions. Some oils may break down faster than others, but you are talking about "topping off". A quart of oil here or there is fine as long as (what was mentioned) the weights are the same.

 

I don't see an issue if they are both the same weight. Aren't the dealers only to use the "official" oil? I have plenty of the Castrol left over from my V8V. The Jaguar AJV8 uses Castrol too.
The V12's they use Mobil1. Castrol didn't make a suitable oil for the V12's?

 

The original factory Castrol 10w-60 (and the "cold weather" 5w-50) both have relatively low HTHS viscosity for their SAE "weight", if that tells you anything.

E.g. Mobil1 10w-60 is 5.7 cP, Castrol is 5.2, Motul is 5.8.

Castrol 5w-50 is exceptionally thin at 4.1 cP HTHS (closer to Mobil1 10w-40 @ 3.9cP than Mobil1 5w-50 @ 4.4cP), so you have a lot of viscosity cushion even if Liqui Moly 10w-60 is abnormally thin (which I doubt).

I've heard that additive packages in different oils may interfere with each other but my impression is the blend of chemicals is pretty similar generally speaking, so topping off or blending are both fine.

 

I just had my oil changed and he said the Castrol was no longer available in 10-60 by the quart. He was bringing back containers pumped out of a drum. Possibly the reason for the change.

 

I could've sworn my local dealer was doing oil changes from a drum too.

 

I service my own. I paid $130 for 12 liters a year ago for 10W-60 Castrol a year ago on Amazon. Now it's $250 for the same, not going to pay that. I did use Motul a couple of times, but the service manager at my AM dealer told me to use Castrol only. Motul has basically doubled on Amazon as well. I did find Castrol 10W-60 at O'reilly's for $13.49 / quart. I don't think it really matters the brand though.

 

I have about 6-7 bottles of the Castrol leftover from the my Vantage. Is there someone around Boston who may want them? Trade for wine?

 

Were I live it is never cold so have always used 10W-60.

I appreciate the suggestion. Have decided to go with Redline 10W-60.

 

Just be aware that Redline oils are all thicker than "normal" oils in your bearings (HTHS is much higher, as esters have higher viscosity index than PAOs). That's why I mentioned 5W-50 in particular, because the 5W-50 has a HTHS that nearly matches Castrol 10w-60, and Redline 15W-50 exceeds it (5.8 cP, that's more than Mobil1 10W-60 as well, compare to 4.5 on Mobil1 15w-50). Usually people go one grade down when using Redline, then they get the better cold start performance with no lost heat tolerance.

The lower kv 100 means the oil pump sees less pressure, but the higher HTHS means anything under full hydrodynamic lubrication (not boundary lubrication) will have increased drag. So going one grade down to match HTHS gets similar bearing performance with lower oil pump power consumption.

 

I may end up going back to Motul 10w-60. Quite a bit cheaper than Redline. Any thoughts?

 

Found this updated article on V8V oil.

https://www.redpants.lol/article-liquid-fools-gold

 

☝🏻 Yup. Same thing happened with Volvo. Oil cap reads “Volvo recommends Castrol” . Until they don’t. Pure marketing deal.

 

I have been using Liqui Moly 10W60 for the past 6 yrs and more than 50k km, no issue what so ever, I buy it from Amazon at 4 x 5L at the time so good for 2 yrs.