1976 VW Bus / Kombi - oil recommendation

Beckstar: I read somewhere that “racing” oils generally don’t have enough detergents for a daily drive, but I read later that many of the “racing” oils in chain stores do have enough detergents

Beckstar: Sorry, what do you mean by “a strong detergent TBN of 9.8…”?

SR5: Overbase detergents are added to oils, not to act like conventional household detergents (that's more like the oil's dispersants job) but to add alkalinity to neutralise acid buildup in the oil from burning hydrocarbons. This is measured by the oils total base number (TBN).

Track only race oils have a low TBN, since the oil gets changed every race or every few races.

Street approved race oils have a high TBN so that you can go a longer distance (e.g. 10,000 km or 12 months) and so can be used on the road. A TBN of 9.8 is high, and this Penrite product is safe to be used for regular street applications, which is what you want to do.

Penrite 10-Tenths are great oils, good heat resistance and shear stability, I have run the 10W40 myself before, it's my favourite grade.

Beckstar: I would be keen to continue using Penrite 10-Tenths if it’s a great oil for the job. I can order the Racing 5 in if needed. I don’t get why Penrite would discourage using this and encourage EDS 10 instead?

SR5: Because Penrite 10-Tenths is designed for high performance race engines, not a 1976 Kombi with a stock 2L engine. It's a great oil, but your Kombi is outside its design brief. A bit like putting steak sauce on ice cream. It won't kill you, but why are you eating that?

Beckstar: concern about compatibility with seals

SR5: Well you are running it now, is it leaking oil more than before? You have the data point here.

Beckstar: I checked the Castrol product selector and it offered only Castrol GTX. Edge is available on their site, but it avoids selecting it. I don’t understand why they would only offer their lowest tier oil.

SR5: The job of the oil company is to select the product that most closely aligns with the recommendations of the vehicle manufacturer. Castrol GTX most closely aligns with the VW 1976 requirements. Some car companies update these requirements for certain vehicles, some don't. Your real issue is with VW / VAG not Castrol / Valvoline / Penrite.
I would happily use GTX 15W40 in your Kombi.

Beckstar: The Valvoline Australia web site product selector offers the Premium Mono 30 as the only option for a 76 Kombi! I know there are many who swear by the mono grades, particularly in the type 1 beetle motors, but that’s not me. I want a modern oil that does a great job.

SR5: I would also happily use Valvoline SAE30 monograde in your Kombi, low volatility, shear stability and no problems with cold starting in Australia.

The real issue is that you want to run a modern synthetic, but you want someone else to approve your decision.

Beckstar: You see, I’ve got this chronic condition called “engineer” ;)

SR5: Then put on your big boy engineer pants and make a decision and take the responsibility for your decision. Or if you don't feel qualified to make that decision, then follow the advice of others who have that job, the people at Castrol / Valvoline / Penrite.

You have many suitable options open to you. There is not one perfect oil, rather a lot of suitable oils.
 
Beckstar: I read somewhere that “racing” oils generally don’t have enough detergents for a daily drive, but I read later that many of the “racing” oils in chain stores do have enough detergents

Beckstar: Sorry, what do you mean by “a strong detergent TBN of 9.8…”?

SR5: Overbase detergents are added to oils, not to act like conventional household detergents (that's more like the oil's dispersants job) but to add alkalinity to neutralise acid buildup in the oil from burning hydrocarbons. This is measured by the oils total base number (TBN).

Track only race oils have a low TBN, since the oil gets changed every race or every few races.

Street approved race oils have a high TBN so that you can go a longer distance (e.g. 10,000 km or 12 months) and so can be used on the road. A TBN of 9.8 is high, and this Penrite product is safe to be used for regular street applications, which is what you want to do.

Penrite 10-Tenths are great oils, good heat resistance and shear stability, I have run the 10W40 myself before, it's my favourite grade.

Beckstar: I would be keen to continue using Penrite 10-Tenths if it’s a great oil for the job. I can order the Racing 5 in if needed. I don’t get why Penrite would discourage using this and encourage EDS 10 instead?

SR5: Because Penrite 10-Tenths is designed for high performance race engines, not a 1976 Kombi with a stock 2L engine. It's a great oil, but your Kombi is outside its design brief. A bit like putting steak sauce on ice cream. It won't kill you, but why are you eating that?

Beckstar: concern about compatibility with seals

SR5: Well you are running it now, is it leaking oil more than before? You have the data point here.

Beckstar: I checked the Castrol product selector and it offered only Castrol GTX. Edge is available on their site, but it avoids selecting it. I don’t understand why they would only offer their lowest tier oil.

SR5: The job of the oil company is to select the product that most closely aligns with the recommendations of the vehicle manufacturer. Castrol GTX most closely aligns with the VW 1976 requirements. Some car companies update these requirements for certain vehicles, some don't. Your real issue is with VW / VAG not Castrol / Valvoline / Penrite.
I would happily use GTX 15W40 in your Kombi.

Beckstar: The Valvoline Australia web site product selector offers the Premium Mono 30 as the only option for a 76 Kombi! I know there are many who swear by the mono grades, particularly in the type 1 beetle motors, but that’s not me. I want a modern oil that does a great job.

SR5: I would also happily use Valvoline SAE30 monograde in your Kombi, low volatility, shear stability and no problems with cold starting in Australia.

The real issue is that you want to run a modern synthetic, but you want someone else to approve your decision.

Beckstar: You see, I’ve got this chronic condition called “engineer” ;)

SR5: Then put on your big boy engineer pants and make a decision and take the responsibility for your decision. Or if you don't feel qualified to make that decision, then follow the advice of others who have that job, the people at Castrol / Valvoline / Penrite.

You have many suitable options open to you. There is not one perfect oil, rather a lot of suitable oils.
I already had my big boy engineer pants on; that’s why I bought Royal Purple HPS. But I’m also a good enough engineer to know there is plenty to learn about specialist fields. The members on here seemed quite knowledgeable hence the reason for the inquiry. All in the name of learning something, and perhaps avoiding a mistake if I’d made one.
 
I did the oil change today. Penrite Racing 10 10W-40 out, Royal Purple HPS 5W-30 in.

I’m pleased with the viscosity change. At 70 deg C oil temp and 2,500 rpm I’m now getting 41 PSI. The factory manual says it should be “at least 28 PSI” under these conditions. Previously with 10W-40, I was getting over 45 PSI at 2,500 rpm (70 km/hr) even when up at 85 deg C, which is a problem because the oil pressure relief was likely opening and bypassing the oil cooler especially at highway speeds. Now, when at 100 km/hr, I’m just starting to activate the pressure relief valve when oil is 85 degrees C, so the cooling system is working right :-)

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High Performance Street (HPS) is what I would use if using Royal Purple products. It's got high ZDDP (zinc, anti-wear) at somewhere over 1000 ppm according to their charts, high TBN at 9.7, and their special Synerlec friction modifier.

Last I looked, they don't add Synerlec or this much ZDDP to their different API approved products. I don't see the point in paying more for Royal Purple and then getting their API oil which is formulated similar to many other products in the market. If you are using Royal Purple get the special stuff, HPS or XPR or HMX are the three that still add Synerlec.

Looking at HPS 5W30, it has a viscosity (KV100) = 11.09 cSt which nicely fits into the SAE viscosity limits of 9.3 to 12.5 cSt. However, look at its HTHS (high temperature high shear viscosity) of 3.8 cP. That's massive! A typical ILSAC 5W30 (GF-6, Dexos1, etc) would have a HTHS around 3.0 to 3.2 cP, a Euro rated 5W30 (ACEA A3/B4, C3, etc) would have a HTHS around 3.5 to 3.6 cP.

According to SAE J300:
- a 30 grade oil has a minimum HTHS requirement of 2.9 cP,
- 0W40, 5W40 and 10W40 has a minimum HTHS requirement of 3.5 cP,
- while 15W40 and above has a minimum HTHS requirement of 3.7 cP.

So RP HPS 5W30 with a HTHS of 3.8 cP is a very very strong oil.

Also look at the ratio of HTHS to KV100, to have that high a HTHS with that low a KV100 points to high quality base stock and a very low polymer VII (viscosity index improver) load. That's very good.
 
High Performance Street (HPS) is what I would use if using Royal Purple products. It's got high ZDDP (zinc, anti-wear) at somewhere over 1000 ppm according to their charts, high TBN at 9.7, and their special Synerlec friction modifier.

Last I looked, they don't add Synerlec or this much ZDDP to their different API approved products. I don't see the point in paying more for Royal Purple and then getting their API oil which is formulated similar to many other products in the market. If you are using Royal Purple get the special stuff, HPS or XPR or HMX are the three that still add Synerlec.

Looking at HPS 5W30, it has a viscosity (KV100) = 11.09 cSt which nicely fits into the SAE viscosity limits of 9.3 to 12.5 cSt. However, look at its HTHS (high temperature high shear viscosity) of 3.8 cP. That's massive! A typical ILSAC 5W30 (GF-6, Dexos1, etc) would have a HTHS around 3.0 to 3.2 cP, a Euro rated 5W30 (ACEA A3/B4, C3, etc) would have a HTHS around 3.5 to 3.6 cP.

According to SAE J300:
- a 30 grade oil has a minimum HTHS requirement of 2.9 cP,
- 0W40, 5W40 and 10W40 has a minimum HTHS requirement of 3.5 cP,
- while 15W40 and above has a minimum HTHS requirement of 3.7 cP.

So RP HPS 5W30 with a HTHS of 3.8 cP is a very very strong oil.

Also look at the ratio of HTHS to KV100, to have that high a HTHS with that low a KV100 points to high quality base stock and a very low polymer VII (viscosity index improver) load. That's very good.
Thanks SR5, I love the data you’ve provided in that analysis! It looks like I can have a lot of confidence in this oil providing great protection and cleanliness to my engine. Yes, I guess it’s overkill on a 70HP flat tappet engine with red line 5,400 rpm, but I like spending a little extra on the extra insurance and that warm fuzzy feeling :).
 
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Does it feel any smoother with the RP Synerlec ?

With Penrite 10-Tenths and Royal Purple HPS, you are certainly running some high end oils.
 
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I didn’t notice it running any smoother with Synerlec. Having said that, I was focussed on temperatures and pressure so may not have noticed.
 
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