HTHS benefits?

[92saturnsl2]

I've heard the term HTHS thrown around here and how it benefits certain applications. I'm not sure the benefit of this attribute.

I own a 2001 Jetta (12v 2.8L VR6) that I use for commuting short trips (3-4 miles each way). It does see infrequent around town driving or highway use.

This winter because of this short trip driving I switched from the Mobil 1 Truck and SUV 5w-40, and 0w-40 I'd been using to Mobil 1 5w30, as the viscosity during cold starts and when oil is not up to temp is lower.

Recently I'd been reading about the HTHS property and how it is lower in the 5w30 weights than in the 5w-40, and 0w-40's.

What is the biggest tradeoff in using 5w30 instead of the recommended 5w-40 in this engine? What would you guys recommend for this vehicle and this type of driving? 75k on engine, no noticable oil burning, with 5-7k OCI.

 

[Dr. T]

The biggest tradeoff is that 5-40's are generally the cuttoff for the European golden standard of an A3 rating. That is, this is generally the distinguishing grade between oils that pass the HT/HS rating of 3.5 or higher. There are a few 0/5-30's that pass as A3 eg. GC, but M-1 isn't one of them because it's a N.A.-origin oil and this spec. is somewhat meaningless in this continent.

However, you ARE using a 'non-recommended' grade in your VW and even though you should be OK for an interval (especially if you keep it shorter eg.~5k). Otherwise, you should switch back to the Euro-recommended 0/5-40 as soon as possible...with the usual exeptions...ie. car is under lease, you only plan to keep it to 100k, it's a beater, it's the girlfriend's, mother-in-law's, etc., etc.,

[ December 09, 2005, 12:41 PM: Message edited by: Dr. T ]

 

[Mitch Alsup]

HTHS tells you something about the characteristics of an oil when it gets very hot and when it encounters massive amounts of shear.

Short commutes do not get the oil hot enough to worry about the loss in viscocity due to heat and shear. And you should not be running the snot out of an engine (high shear) before it fully warms up anyway.

Certainly xW-30 oils will be fine for winter, probabily prefered. If you live above the 40 parallel, you could even get away with xW-20 oils and save on engine start up wear for the cold end of the year.

 

[Burbanite]

If you want to use 5w30 with an A3 rating you can use Redline Synthetic. Their 5w30 & 10w30 have an HT/HS of 3.8 and their 5W-40 has an HT/HS of 4.6. All three meet the A3 spec which is an HT/HS of >3.5. Just another option for you.

 

[Big O Dave]

Some other Xw-30's that are A3 rated are:

GC
Valvoline Maxlife Synthetic 5w30 & 10w30